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 New Dmoco 6 Axis Rig Driven by DMC16 
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Well i picked the wrong week to be welding :( Its actually been quite hot in Manchester but got to get this crane out of my living room . Taking it to me mates workshop should be able to swing the boom round without causing any damage .
[flickr]Image2016-06-08 19.24.58 by D 1, on Flickr[/flickr]
[flickr]Image2016-06-08 22.01.31 by D 1, on Flickr[/flickr]
Welding not the perfect solution for this kind of thing you do get a bit of heat distortion . But the bearing mounts are bolted into place so any fine adjustment can be made at the end . Welding does give ya very rigid structure though so its all swings and roundabouts. I could make it even more rigid by welding a thin 1mm skin to the frame but think that will be over kill .I will clad it though just to make it a bit safer dont want any hands getting wedged in their
Just got to fit ballscrew to boom and we should be ready for a bit of movement :D
D1


Wed Jun 08, 2016 2:20 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Ooooooooooh, clad it in plywood! :) That thing is going to be a beast. But a good beast.


Wed Jun 08, 2016 4:52 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Doug K wrote:
Ooooooooooh, clad it in plywood! :) That thing is going to be a beast. But a good beast.


You read my mind :D Well MDF get a nicer finish . See ya been tweaking your beast to ;)
D1


Thu Jun 09, 2016 12:12 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Another small crane their seems to be more appearing we all seem to be using similar size with a few different drive methods . Nice to see high speed is possible Ok theirs a lot of shake at the end of shots . But with careful editing that hardly matters as the end results show :D .
My build is taking far to long i think its a case of if ya build one and use it yourself its worth while . if ya build them to sell forget it :( Just a word of warning to you money orientated people out their .

D1


Sun Jun 12, 2016 2:07 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
This rig was made by Klim in Kazakhstan - he started building it in 2014.. it's fast and relatively light weight. Perfect for small scale work...

It uses Harmonic Drive gears with industrial brushless servos - which he obviously likes to push hard... Control system is Mantis.

On high speed moves it can be difficult to avoid some shake at the end - robot arms have the same problem. It can be alleviated by carefully ramping of the start and stop, but as D1 agrees, generally the stop is not such a priority, since it is rarely used in the final cut. Even so I think most of the moves are pretty good?

BTW D1 - if you build to sell - better to make a prototype first perhaps? :)


Sun Jun 12, 2016 7:08 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Ah thought it might be Mantis . Think i will have to get myself a servo to play with :D Unknown territory for me but must get this rig finished first !
Hi Gerald i dont think i will be mass producing rigs . As with the case with the current one its bespoke using certain parts that we had . I am building up quite a good CAD library of parts i like and seem to work well . So each build can use these if they fit into the scheme . The head and boom design works well for me .I know their is thoughts on how the boom is actuated . I do like my ballscrew ram its zero back lash and very rigid . It creates a triangle from the fulcrum down the main turret and back along the boom . Think this offers a lot more stability than just having a gear at the fulcrum . The only issue i have its difficult to integrate with a CG program that tends to use angular ration to describe position .
Any ways final push week got another job on so it has to be done .
[flickr]Image2016-06-12 21.01.28 by D 1, on Flickr[/flickr]
[flickr]Image2016-06-12 20.51.21 by D 1, on Flickr[/flickr]
[flickr]Image2016-06-12 20.50.47 by D 1, on Flickr[/flickr]
D1


Mon Jun 13, 2016 12:58 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hey D. Yeah the triangulation is a nuisance for CG, but could be dealt with if determined... :)

But do make sure that the line between the pivots at each end of the drive is exactly parallel with the drive,
otherwise the geometry gets even more tricky to interpret.

Maybe also consider offsetting the bottom pivot further out from center. In the extreme, when the back of the arm is at maximum height,
the angle between the arm and the slider will grow very small, to the point it is in danger of locking up?


Mon Jun 13, 2016 1:41 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
geraldft wrote:
Hey D. Yeah the triangulation is a nuisance for CG, but could be dealt with if determined... :)

But do make sure that the line between the pivots at each end of the drive is exactly parallel with the drive,
otherwise the geometry gets even more tricky to interpret.

Maybe also consider offsetting the bottom pivot further out from center. In the extreme, when the back of the arm is at maximum height,
the angle between the arm and the slider will grow very small, to the point it is in danger of locking up?



Got feeling that dealt with may involve maths and you know me on that subject :(
I have left all pivot mounting points with a slight amount of adjustment when i do the final assembly everything will be lined up and tightened down so everything will be aliened properly
Yeah pivot below fulcrum as been clamped in various places. Thing i couldn't work out in DesignSpark so just a bit of real life manipulation was called for . Seem to have reached a sweet spot between length of ballscrew how much leverage i wanted and no lock up or fouling on anything . I think ;)
Just about to clad it in wood/mdf so that should make Doug happy !
D1


Mon Jun 13, 2016 2:17 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
She's turning out to be one beautiful, massive machine. Its very interesting to watch it come together. I hope you will shoot some tests with it before letting it leave for a new home. Do you think it will do some realtime multipass? If so, it would be really nice if you could post some results along with some behind the scenes of it running.


Mon Jun 13, 2016 7:10 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Bit to massive ! Will test muiltpass real time on i wide lens dont think their will be any problems 100mm macro may be a different story .
Luckily the end use is stopframe so none of it a issue really .
Tie bars and head tested works well 15kg counter weight !
[flickr]Image2016-06-13 15.07.48 by D 1, on Flickr[/flickr]
D1


Mon Jun 13, 2016 1:29 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hi, D1, looking good, you could almost pass it off as a portable rig with a broad shoulder on each end ;)

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Tue Jun 14, 2016 3:51 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
D1, I look forward to hearing about the results using real time. My guess is that you may get some wobble particularly on starting and finishing, unless you ramp really slowly and gradually.

Wobble or sideways oscillation as you move the arm round. I hope I am wrong and as you say, it's mainly for animation.

Edward


Tue Jun 14, 2016 6:01 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Can I ask a question a bit out of context, since we are all cosily gathered here:)

Has anyone had any luck milling aluminium with one of these super high rev routers? And by milling I mean deep, like a through pocket in 10mm alu or similar depth. Don't you get the bits easily clogged at such high res, unless you do super fine passes? And if you do super fine passes, doesn't it take forever?

With a conventional mill, even a small Sieg SX2 like D1 and I have, you can use a 10mm end mill at 1000 revs or so and happily cut away fairly quietly. I am just wondering whether it is better to adapt a conventional mill than go the router way and perhaps be disappointed?

Any thoughts?


Edward


Tue Jun 14, 2016 6:15 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Alright! Now that is a crane! Can't wait for the skinning to begin! And what Edward said about that big ol arm, I find that if I have the boom either on the 0 or maybe off at 35deg +/- it is very stable and my moves start and stop smoothly. If, I plot a move where the boom is swinging from the aforementioned across, like a big swinging move, I have to go a lot slower, in realtime. But when things go over to stopmo these issues disappear. Not sure how the DMC works but in Mantis I can adjust the fps while shooting realtime. Then is the shot looks good I switch over to stopmo or go into DSLR mode to do model stuff. Really want to see a vid of how the DMC works in the Arc window in DF. Very curious.

Side note.
Having worked with DF and Arduino I remember my rig being very smooth when moving from frame to frame. Not keyframe to keyframe but frame to frame. I recall the sound of the motors ramping up and down between each frame and my rig moved very smoothly. Now with Mantis I don't find the same smoothness between frames. The ramping seems to be calculating between KFs which means my rig has a jerkiness to it. Not a problem at all when doing stop motion but just an observation. If you checkout some other videos online where the person is shooting using the Arduino with DF you can hear and see what I am talking about.


Tue Jun 14, 2016 8:07 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Edward,

I have a big Bridgeport milling machine in my garage which is manual, no CNC. I want to get something that runs Mach 3 CNC and am planning on getting a big router. I like the openbuilds OX router. Its true that I could modify another Bridgeport for CNC or a little Harbor Freight mini-mill, and these would do deeper passes, cutting a pocket much faster.

The router is going to take more time to cut an equivalent part, but its made for making large, flat things. I hate making large plates like dolly decks and such because I have to take the vise off the mill and clamp the plate down with T-nut clamps. I'm always afraid of what happens if that big plate comes loose and gets thrown out of the mill, mostly because I don't trust the stepped hold-down clamps. Then I have to put the heavy vise back on the mill and take time to get it square with the mill table again. So something that can hold really large plates and cut them with precision would be better for me than another mill, even if it did have CNC. The router can make big gears and sprockets like D1 makes with his laser cutter. The large OX can hold plates up to 750mm by 1000mm. Although I have no plans to make parts that big, its nice to be able to if the need were to arise.


Tue Jun 14, 2016 11:17 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
SL,
I thoroughly agree about the benefits of machining large pieces with a router and I too hate the rigmarole of clamping pieces and squaring up the vise, etc. and that's why I would like to hear from people who use routers to mill large pieces, so that they tell us the problems and limitations of the routers.

Looking at D1's picture of the black pan/tilt head 6 posts above, the horizontal part that holds the pan pivot of the head is, I reckon, about 300mm long. It has a large through pocket, it has a hole for the pivot axis as well as other smaller holes, it also ends in a semicircle. the thickness is probably 10mm. This would be a typical piece to machine and just about the limit of travel for a small conventional mill on the X axis. Could this be done successfully with a router, and an estimate of how long it would take, as well as other pitfalls.

I'd like to go the router route, but I have only seen small parts being machined on YouTube, and small parts are rather easy to machine with a conventional milling machine. D1 himself wasn't too sure about the routers...

Edward


Tue Jun 14, 2016 12:05 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Ah their seems to be a bit of a conversation rather than me waffling away to myself :D
Hi Edward how did your shoot go with your rig ? well i hope . Yes i think theirs going to be wobble with such a long boom but not my choice and as you say for animation it will be great . If i ever build another one i would prob take 500mm to 700mm of the length of the boom from the fulcrum and about 300mm of the height of the turret .
Really not enjoying this build now . If its your own rig ya do a bit when ya fancy and prob let things go because you know you can keep a eye on things. When its for somebody else everything as to be spot on . No temp fixes it as to be right and last without constant monitoring no easy task .
Hi Doug yes DMC will let you run moves at different speeds if you cant physical move the rig fast enough. Lets face it in stopframe you could go from full speed to a stop then full speed again . A move that just wouldn't be possible no matter how good a rig you have . Just to make ya happy by way a bit of wood
[flickr]Image2016-06-14 12.26.08 by D 1, on Flickr[/flickr]
Got boom ram finished very happy with this and its in the CAD library now . You can by these but not been able to find any without back lash . The one on the Volo is a ready made item but not sure on the specs of it.
[flickr] Image2016-06-14 19.00.24 by D 1, on Flickr[/flickr]
On the subject of mills routers think already mentioned i am planning to build one specially for plate ali . Me little mill is great it takes its time its really quite but its to small in fact any mill is to small Z Y . So router with a spindle motor is the way forward built from scratch with the help of the little mill it shouldn't be to hard . Going to get most of the bits from https://cnc4you.co.uk/ really good company to deal with i ordered a ball screw on Monday it came today :D
As for speed yes ya can go fast incredibly noisy though.

Ps new lathe turned up wouldn't recommend it but it fits the space got a Axminster engineer in tom to have a look at it :(
[flickr]Image2016-06-14 19.12.44 by D 1, on Flickr[/flickr]
D1


Tue Jun 14, 2016 12:27 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hi Edward ya type quicker than me ! Think it as to be the router way if ya can deal with the noise. If i ever build another crane i am hope the turret can be machined out of 10mm ali . My PT head is mainly 15mm ali it takes all day with the X2. Will keep my little mill at home the big router will go in my mates workshop .
D1


Tue Jun 14, 2016 12:32 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
I think that lathe is the same one that Axminster had when I went to the lathe class. Or maybe it was the bigger model, but I did like it.

Re routers, I don't think the noise will be so important for me now that I am having the garage replaced by a proper brick construction, with cavity walls and insulation in between. I am also having triple glazing for the windows and overhead skylight. They won't start the works till August now, so I am very impatient. The routers do sound horrifically loud though. In your case and with your eperience, self building it from scratch is the best option, as you already have the small CNC for milling the parts. I may build one too alongside you, depends on timing. But first I will finally open the b Fusion kit box, still unopened:)

Edward


Tue Jun 14, 2016 12:51 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
D!, just saw the video of the router that you posted, my head is still reeling from the noise, I just couldn't watch the hole length. It reminds me of the 2.5cc ETA diesel engines that I used to use for my racing model airplanes when I was young, you need noise damping headphones, otherwise you will go a bit deaf at certain high frequencies, like I did, very dangerous. Also, I don't understand why it keeps jumping from pocket to pocket instead of finishing one pocket first, could it be in order to disperse the heat?

Edward


Tue Jun 14, 2016 1:00 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hi Edward i am quite looking forward to building myself a router it will make a much needed change from cranes and all thinks camera orientated. Actually while we are on that subject ware do you get your servos from . Their not as easily available as steppers are they .
Back on routers they are noisy i spent about a year next one when i last worked in a big workshop . Not only noisy but as you say a pitch that really gets ya teeth rattling horrible ! Think something like this is quite easy to make http://www.lagunatools.com/cnc/IQ_2 but i will prob lower the spindle dont need much travel on the Z and beef up the over all thing . Steel box mainly so should be a lot more rigid than the common ali extrusion ones . All the big routers i have used in the past have been of steel construction and weigh a ton had to get a hi ab in to move it .It may be a idea to build it into a insulated cage we will see. . If you find any useful links on building routers let us know i will do likewise . I dont think you will be able to buy off the shelf what you want .
D1
Ps not sure why it jumps about but you do get weird tool paths with CNC i get used to it . Def not for heat watch end of vid not much heat apparently !


Tue Jun 14, 2016 2:12 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
D1, depends what servos you want. The cheap Leadshine I got them directly from the US.

The much better Delta AC servos, I got them from Damen CNC in Europe. Expect to pay around £500 each though, including drive. (The drive plugs to the mains 240Ac)

https://www.damencnc.com/en/components/ ... -drives-b2

Take a look at their CNC machine too. I liked dealing with them.

The Leadshine are cheap, but the software is lacking and they are not as smooth as the more expensive brands, plus you need a power supply. Not bad as a starter though.

Going the servo route is usually quite expensive, but it's probably worth it. There are others that I will be testing, so no comments yet.

Edward


Tue Jun 14, 2016 3:17 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
A flurry of activity... :)

Agree with Edward. But the cheaper Leadshine servos are quite servicable and because the drive is very compact it can be integrated into an existing stepper drive box, and even share the same power supply. Tuning requires a bit more trial and error but can still achieve usable results. Whereas with the industrial style mains units like Delta, you need more space for the drives.

Doug - re moving between frames in stop mode. Mantis uses the same acceleration and jerk settings which you have setup for jogging. So if jogging short distances is not smooth, then the same will happen when moving frame to frame in stop mode. DF applies a reduced jog accel rate for frame to frame moves - default is 1/8th normal speed. I could add a similar option in Mantis, though I've not had an issue myself, since I just make sure the jog settings are appropriate. In fact DF does not have a jerk setting, so Mantis can be potentially smoother, while still moving efficiently if you reduce jerk appropriately. As mentioned, axes like the boom is where you will notice this most - so just tweak the boom accel and jerk settings for best response. (Note - Velocity is not important for frame to frame move, since in a short move it is unlikely to reach any maximum that you have set for normal jogging.)

BWT - D1 - you might want to glue some sound damping inside the mdf? Potential there for some resonance from the motors...


Tue Jun 14, 2016 5:16 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Thanks Gerald, I figured it was probably something I hadn't set correctly.


Tue Jun 14, 2016 6:39 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hi Doug Well no right or wrong - just what works is good. The diagrams below might help explain principles. This thread seems to go in all directions so I hope it's ok...

Attachment:
ShortAccelNoJerk.JPG
ShortAccelNoJerk.JPG [ 30.26 KiB | Viewed 10514 times ]


The image above shows a standard move profile like you would get from Dragon or any system without jerk control. The (grey) velocity curve moves in a straight line until it reaches a maximum velocity ceiling, then continues at constant velocity before ramping down at the end. By reducing the acceleration rate you would increase the time taken to move from start to finish and hence shaking would be reduced. However there is still be some potential for shake when the accel kicks in and when it transitions to constant velocity. You can see this from the blue accel graph, which jumps up and down at these transitions.

Attachment:
ShortAccelWithJerk.JPG
ShortAccelWithJerk.JPG [ 31.11 KiB | Viewed 10514 times ]


In this example I have added smoothing which is the same as reducing the jerk value. With judicious use it "sandpapers" the transitions, so there is less chance of shake. You can see the accel curve now ramps up and down smoothly. Note - If you decrease jerk too much then it will slow down the response to the point it becomes plain sluggish. So some experimenting is required to find the sweet spot. In essence using jerk allows you to keep acceleration rates reasonably quick, and the move time short, while still reducing shake.

The way to understand jerk better, is to remember it is the "rate of change" of acceleration. So when it is high it allows accel to change rapidly, and when it is low it limits how quickly accel is allowed to change, which leads to smoother movement.

With axes like pan tilt where there is low inertia, this is less important, but for your boom it is quite critical...


Tue Jun 14, 2016 8:38 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
A flurry of activity indeed i will have a look at the servos but a bit to expensive for the things i do . But their is always the challenge of making things go faster :D
Hope to get crane assembled next two days so will see how much wobble that boom causes. What i learn from this one will inform the next if i ever build another one that is.Not in the mood at mo but if i do do it will be for me and a real time rig . Router first though :D .
Dont mind things going of topic at all as its nice to discuss things . The Axminster man just been very helpful their was a bent grub screw on the feed selector . So a bit happier with my lathe now cant fault Axmuinster though.
D1


Wed Jun 15, 2016 1:26 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Talking of routers, one thing that I saw someone do is to use a Sieg X2 milling machine and remove all the XY axes till the mill base is bare and then swap them for Hiwin linear rails.

The X and Y stages were bolted to a thick steel plate which in turn was bolted to the bare base of the mill. So you gain in rigidity and your X axis can be as long as you want, within reason. You are still confined with the Y axis to maybe some 150mm. By using linear bearings you get the precision, no need to adjust gibs, and perfect squareness, which should yield perfect round holes and pockets.

I may be tempted to go for this option, at least in the interim. Less noise, lower rev milling, more torque, less vibration.

Opinions?


Edward


Wed Jun 15, 2016 5:28 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Aaaaaaaaahhhhhhhh! I see. I thought that jerk and accel delt only with the jog to settings in the setup window. Did not know this. I'm sure Gerald mentioned it somewhere in some email but my brain can be slow at times.

EDIT:
Ach! Sorry Gerald. Thanks for the tip and I am going to check out my new/not so new knowledge.


Wed Jun 15, 2016 11:10 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
I will concentrate on the mill discussion not been a Mantis owner but glad ya solved your problem Doug.
Hi Edward my opinion is its a shame to mess with a little mill that is good at certain thing but bad at others . The max i can cut in the y with a 6mm cutter is 96mm . Even if you adapt the X2 i dont think you will manage to get much more in the y. Another problem the motor just isn't fast enough for ali. I could use a quicker feed rate if the motor was faster and this why it take so long to machine something . Not a problem if ya got all the time in the world but big pocketing jobs do take a day . I would keep the X2 for milling little jobs its great for shaft flats etc and build a your own the X2 will help a lot .
You dont have to mount a spindle motor on a router you could get the same motor as the X2 . I just replaced mine . But motors can be easily changed bed size cant Back on crane got bearing mounts shimmed out and all is true now ready for boom and ram fitting and aligning . Toms job so on scheduled Yeah !
[flickr]Image2016-06-15 14.51.40 by D 1, on Flickr[/flickr]
[flickr]Image2016-06-15 19.56.48 by D 1, on Flickr[/flickr]
D1


Wed Jun 15, 2016 12:42 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Thanks for your opinion D1. Yes, 10cm on the Y is a bummer!


Wed Jun 15, 2016 2:38 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Ah, you guys with your fancy routers! I have trained Canadian beavers to work wood and metal for me!They also serve as attack beavers!


Thu Jun 16, 2016 10:05 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Well, you know…men and their toys!

Talking of toys, I have just ordered an internal micrometer. I am fitting a few bearings and using my boring head but the old vernier calipers are not accurate for that task. So I'm looking forward to using it. It's Father's Day on Sunday, so that's my present to me sorted:)

Edward


Thu Jun 16, 2016 11:24 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hi, Di, I expect you have an email from Zapp, if not plenty of reduced prices for CNC here: http://www.zappautomation.co.uk/
May interest you also Edward.

200Kg for the CNC router they are selling ? Typo probably ;)

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Sat Jun 18, 2016 6:17 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hahahah, I got the email from Zapp too, someone we know instantly mocked the 200Kg weight….

Sounds quite heavy compared to others, but maybe it's right.

I would certainly consider it, as it looks like a proper machine and I can see it working before buying. I have always had a fantastic service from Zapp.

Still a lot of research work to do before I decide on one.

Edward


Sat Jun 18, 2016 9:26 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Hi Mike Edward yes this seems better but still think you could build ya own . Thing that concerns me with all these smaller routers is they have a single ball screw centrally mounted bellow the table which moves the gantry. This is fine i suppose for a very small table but i think these are pushing the limits when you go larger .8x4 tend to have a rack left and right and if my memory serves me correctly separate motors for each side driven simultaneously. With a single ballscrew down the middle side loading must become quite pronounced when the gantry is extreme left or right . Think it going to be double ballscrew for me driven by two motors from the same step direction single. Not done that before but sure its possible .
Ps i have my living room back Yeah :D


Sat Jun 18, 2016 10:54 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Not sure if you need to be that concerned, as these travel on linear rails. I have my robotic stand with all its weight resting on two parallel linear rails and it doesn't seem to matter where I place the (in this case) belt. I have it to one of the sides and it perfectly OK.

Today I have been playing with my new inside micrometer, what a lovely toy to have! Each little line is 0.01mm and after a little bit of practice I seem to be getting consistent results. It comes with a calibrating round plate with a hole of 4.997mm at 20degrees C. Because the measuring prongs are cylindrical, the natural tendency is for it to slide to the middle of the hole so as to obtain the right measurement. A very gentle bit of rocking is all that may be needed for encouragement.

By contrast, I have been comparing it to a normal vernier caliper and it is difficult to get repeatability with these, it all depends on your finger pressure that may vary a little from measurement to measurement. My favourite micrometer is the Digital Mitutoyo, it always reads with the same consistency.

For those who may not know, these micrometers have a ratchet wheel that you tighten to the point where it starts to slip once the correct pressure has been applied, so there is no danger of you applying too much force and get inaccurate readings. But you still need the skill to place the prongs exactly at the widest point of the circle.

Hopefully, with my new boring bars with inserts, I will now be able to bore very precise holes for bearings.

Edward.


Sat Jun 18, 2016 1:03 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Think will still go for two ballscrews it seems a necessity on 8x4 ft table routers . I hope to build a 4x3ft so it pretty close to 4ft gantry either way . With routers you are applying quite a push pressure which changes direction when cutting different shapes. In your stand its a more constant load gravity . I find chatter is the big problem in routers/mills its that tiny bit of movement and the bit jumps about.
As for measuring toys thats the joy of CNC if its set up right you never need to measure again :D But lets face it my tolerances are not that great . A tip with bearing seats i make then slightly smaller so bearing cant fit .I then heat the up the bearing seat if thats possible in the oven and the bearing slips in nicely and when it cooled its not going any where . Do the same with my land rover hub bearings
This will make you laugh just found another fault with my new lathe :( Hit the emergency stop button and nothing happened ! Another call to Axminster me thinks .


Sat Jun 18, 2016 1:34 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
I still think that with a medium preload of the four linear blocks, the thing is not going to sway anywhere, but it's only a hunch, I don't really know. It's just that having two ballscrews for one axis and two motors in sync seems to be taking things a little too fanatically:) And it may create other problems...

Yes I have used the heating trick for bearings, and I agree, so much easier with CNC, provided the machine is really perfectly squared, otherwise you holes may be slightly out of round. And with the little Sieg SX2, they probably are, at least my axes are noticeably out of square and there is little you can do about it. With an inside micrometer, you would soon find out if your CNC'd holes are perfectly round...

Re your lathe, these things do happen, you may have been unlucky. I know that the e-stop on my Wabeco works because I have pushed it by accident a couple of times!


Sat Jun 18, 2016 1:57 pm
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Looking at the price (not the Megga) for a Zapp kit you might want to consider looking at this site Edward, they have various options of ready built units with options for routers, it is not the best of sites when it comes navigating to the various options.
http://stoneycnc.co.uk/

200Kg for the Zapp may be - Stoney mega with similar footprint 250Kg.

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Sun Jun 19, 2016 1:26 am
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Post Re: New Dmoco 6 Axis Rig Driven by DMC16
Ah i like those more and they do use two ballscrews connected by a belt . Still wonder if separate motors is a better option the only thing that concerns me with separate motors is the jolt when you power up it may not be the same for both . So in that case a belt may be better ?
Price not to bad either ?
But like building things so thats fun for me . Must get out more :(
D1


Sun Jun 19, 2016 3:02 am
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