Throw away your short belts - direct drive.

[lobster2b 0]

So, i got everyhing, and my ultimaker is preatty butchered right now, should be able to get it running in a few hours though.

ive used the wooden part with the loop and a washer, with the m3x16mm bolts.

I have one request, the "wave" that connects the stepper side, to the frame side is interfering with the bolts, making me screw them in at an ange, almost breaking the printed part. if you where to invert the wave, or just make it straight would allow easy insertion of the bolts, and screwing them tightly without stripping the bolthead..

I am looking forward to get it running now, hopefully il hold untill i can make me a abs version of it.

 

[snowygrouch 1]

Hi,

Yes I think the problem was that for a couple of weeks I had the wrong STL model uploaded to my

website.

I fixed this a few days ago. So go to my website, download the STL file and compare it to what you have,

probably you need to get the printer going well enough to print again then print out 2 new proper brackets.

Apologies for that.

C.

 

[lobster2b 0]

No worries, i got it assembled, and i did print the UM handle, just to test it.

Printing ABS, using acetone to wipe the first layer of raft, on a hot bed at 85*c measured, 100*c temp set in ulticontroller, covered with kapton tape, and 260*c printing temperature.

 

And it came out as a masterpiece. perfectly level, straight as a ruler and no artifacts from belt tension.

Il download and print them sometime this week, i did damage the ones that is assembled, but its mostly rotary tension, so i think it should be ok. But il print new ones, before this one fails

 

[IRobertI 516]

I actually found that my machine got louder when I converted. Or maybe not louder, but it changed the pitch of the noise to a really annoying high pitch sound. I'm waiting for parts to change my brackets though and I hope that will help a bit. I'm also thinking of replacing the belts (they've stretched a lot over the year or so I've had the machine), I've ordered new pulleys and I'm thinking of changing to the banana bushings since mine are starting to crack. It'll be a bit of an upgrade I hope

I also put the motors on the left and next to the feeder, seemed more logical and it's easy to just switch around the wires of the motors.

 

[snowygrouch 1]

The loss in XY drive friction is because the motor and XY shaft no longer have

any vertical load on the bearings. So yes, a good thing.

Those new XY blocks look like a pretty good idea. I might try those in a few weeks, I already snapped

one of the little wooden arms. The wood for the machine is (mostly) a great idea, but I wish UMaker

had just done the case from wood and left the smaller parts to something a bit more viable for

small parts. Annywayy

Regarding the noise:

You can get AV mounts for steppers, (I bought some of these actually), but they remain untested and so I cannot say how much positioning degredation will occur after fitting them. Since the only damping method is to allow the motor to move relative to the case....could be its negligable.

http://www.astrosyn.com/section.php?xSec=44&xPage=1

They were pretty cheap, I think something like 8 Euros each.

C.

 

 

[IRobertI 516]

This is what I'm planning at the moment. I'm thinking it should be possible to add some thin rubber between the front part of the assembly and the case to at least reduce vibration a little. The mounting holes are bigger than needed to allow for adjustment (my current bracket is off centre a fair bit) and it should help "decouple" the bracket a bit more from the wood. Might even add tiny rubber washers on the inside of the case as well. No idea what to use though, old latex gloves? edit: I actually have a ton of rubber o-rings, those should work nicely. I should make a groove for a big one on the front.

The yellow bits are brass standoffs that I'm currently waiting for.

 

[lars86 42]

The original ebay link for the couplers has expired. Would these be a good option, or is there a better retention mechanism?

http://www.adafruit.com/products/1176

 

[owen 19]

The original ebay link for the couplers has expired. Would these be a good option, or is there a better retention mechanism?

http://www.adafruit.com/products/1176

 

I'd say they would be OK.

I got some that have a single screw onto each shaft that look like that and it seems to work fine.

Only done the Y motor so far (for a month or 2 now)

I've just finished my X motor bracket so I think I'll put it on today.

 

[snowygrouch 1]

Im sure it probably "works", but I would still suggest its well worth doing another couple of hours

of "googleing" to find a pinchclamp design. The grub will put alot of eccentricity into the coupling

and its not designed to accomodate that - only angular misalignment.

Im just being a typical moaning engineer, so take that into account as well. But since the whole point

of this modification is to get the best possible performance from the drive system it seems

a shame to compromise one of the most important parts of it....

Im sorry I dont have good info on USA sources for this kind of stuff....

C.

http://www.ebay.com/itm/1PCS-5x8mm-Shaft-Coupling-5mm-to-8mm-Flexible-Shaft-Coupler-Connector-/220877879583

https://www.tindie.com/products/diyourfaceoff/cnc-5x8mm-motor-shaft-coupler-5mm-to-8mm/

http://www.fonder.com/shopping/itemDetail.html;jsessionid=5D813316EDD15EDF35CEA652BDCC09EF?itemId=353622472&lang=en&categoryType=1

http://www.amazon.com/5x8mm-Coupler-Flexible-Couplings-26x26mm/dp/B00A2FVGVU

GOOGLE> "5x8mm flexible shaft coupling"

 

[owen 19]

Just realized mine have 2 screws for each shaft

Australian Supplier

https://www.bilbycnc.com.au/DispProd.asp?CatID=9&SubCatID=89&ProdID=PtCoup5-8

 

[lars86 42]

Im sure it probably "works", but I would still suggest its well worth doing another couple of hours

of "googleing" to find a pinchclamp design. The grub will put alot of eccentricity into the coupling

and its not designed to accomodate that - only angular misalignment.

Im just being a typical moaning engineer, so take that into account as well. But since the whole point

of this modification is to get the best possible performance from the drive system it seems

a shame to compromise one of the most important parts of it....

Im sorry I dont have good info on USA sources for this kind of stuff....

C.

http://www.ebay.com/itm/1PCS-5x8mm-Shaft-Coupling-5mm-to-8mm-Flexible-Shaft-Coupler-Connector-/220877879583

https://www.tindie.com/products/diyourfaceoff/cnc-5x8mm-motor-shaft-coupler-5mm-to-8mm/

http://www.fonder.com/shopping/itemDetail.html;jsessionid=5D813316EDD15EDF35CEA652BDCC09EF?itemId=353622472&lang=en&categoryType=1

http://www.amazon.com/5x8mm-Coupler-Flexible-Couplings-26x26mm/dp/B00A2FVGVU

GOOGLE> "5x8mm flexible shaft coupling"

 

Thanks for the input Grouch. No deaf ears here... I'm an ME and CNC machinist. Eccentricity aggravates the hell out of me! hahaha. I'm pretty psyched to get X and Y direct driven, and sporting those upgraded pulleys!

I think that I'll design an anti-backlash Z nut to keep the platform repeatability up. My experiments of attaching weights to the underside of the platform and using rubber bands to preload it to the side have gone really well. I think a third linear bearing at the front would do really well. I'd wager a lot of the "ringing" that people see, is in the bed, not the head.

Between these two styles, do you have any input?

http://www.amazon.com/5x8mm-Coupler-Flexible-Couplings-26x35mm/dp/B00A1YT1ZU

http://www.amazon.com/Reprap-Couplers-printer-Mendel-Prusa/dp/B00BS58GDY/ref=sr_1_1?ie=UTF8&qid=1367849238&sr=8-1&keywords=5mm+8mm+shaft+coupler

 

[snowygrouch 1]

I have never tried the 2nd coupler style, and have no experince of it.

Sorry, however it looks like is a bit better at giving vibration isolated coupling..perhaps it might

reduce the noise a bit. But I cannot make out from the pics if its a real bona-fide "zero backlash" coupling

or a not. The ones with the plastic rings and 4 little "bulbs" are really good for allowing for

misalignemnt and play of all kinds, but also pretty skeptical about their angular timing prescision.

I always liked the 1st style just because its always used on engine throttles, which have to maintain

perfect angular alignment. But no idea...perhaps the 2nd one is also good....

C.

 

 

[snowygrouch 1]

http://www.sdp-si.com/D795/79501184.pdf

These look great, but unfortunatley not available in the shaft sizes we want.....

Perhaps you can get something like this in a 5>8mm size.....

http://www.automotioncomponents.co.uk/en/catalog/rotary/flexible-couplings/plastic-insert-couplings/r3048

These also look perfect, they have a solid lump of silicon bonded to each end, so should be

great for vibration damping, and probably stiff enough in rotation. However, again

not available as standard in 5>8.

I might phone them tomorrow to see if they will do some specials. I must admit

my UMaker does sound like an angry Dalek.

 

 

[lars86 42]

I have never tried the 2nd coupler style, and have no experince of it.

Sorry, however it looks like is a bit better at giving vibration isolated coupling..perhaps it might

reduce the noise a bit. But I cannot make out from the pics if its a real bona-fide "zero backlash" coupling

or a not. The ones with the plastic rings and 4 little "bulbs" are really good for allowing for

misalignemnt and play of all kinds, but also pretty skeptical about their angular timing prescision.

I always liked the 1st style just because its always used on engine throttles, which have to maintain

perfect angular alignment. But no idea...perhaps the 2nd one is also good....

C.

 

 

Cool, thanks. I went with the spiral cut versions.

I've got an MK7 drive gear on the way too for a full, over the top extruder drive redesign.

 

[olivierc 3]

Hi, I'm interested in doing this upgrade, I have got the coupler, and I ordered the shafts, but I have a quick question that might sound stupid: How to you cut the rods to the right length? Those are solid steel and I don't think I will be able to cut them with a simple iron saw.

 

[IRobertI 516]

That's what I used to cut mine, a really dull blade to boot. Took a while but I got there eventually On the second one I got lazy and used my dremel though.

 

[olivierc 3]

Oh ok, I was afraid I would not be able to scratch it. Thanks for the tip.

 

[lars86 42]

For cutting stuff like this, it's hard to beat a composite blade. Bang for your buck --> 4.5" angle grinder with a composite blade.

I'm halfway through this conversion... one of the 2 shafts I ordered has too much runout. Luckily, I ordered through Amazon, so they are overnighting me a replacement. Between this and replacing all the pulleys with higher quality ones, this thing is gonna be smooth!

 

[olivierc 3]

Yeah I just sent the money for the pulleys too, I'm waiting to receive them to do the mod.

 

[ian 32]

Morning Calum. :-)

Can I ask, is it possible for you to share with us a few good close up photos of your print surface quality ? I would be really interested in seeing what you have achived with your direct drive model ! :-)

Thanks.

Ian :-)

 

[snowygrouch 1]

Hi Ian,

I only have a rubbish webcam, which makes useless pictures that do not show any useful level of detail.

I think the potential of the direct drive setup will only be realised with good pulleys.

For me the greatest benefit is just not having to adjust the short belts. The positioning is obviously

better. But how much benefit depends how well setup your belts are.

However there is also a very measureable reduction in moving friction because the load on the bearings

is reduced alot. Replacing the shaft endcaps produced another similar jump in friction reduction.

C.

 

 

 

[kristen 0]

I see you've got yet another new motor mount design up (really at version 9 ?). Any tips on slicer/print settings for the best results ?

I'll probably be pulling the first one off my printer before you get a chance to read this. Thanks for continuing to work on it

 

[thingster 0]

If anyone is using larger couplers you can give my 'artistic type' motor bracket a try. Its designed to take couplers up to 34 mm in length and 25 mm in diameter.

 

[kristen 0]

Calum, could you post up some of your previous motor mount designs ? I like the new springy mount in theory, but my printer is having a fit jumping from the support material to the thin side features. I'm not sure if it's just a retraction issue, bad filament, or a need for better fan ducting, but unless I can sneak a couple prints into the Stratasys, I'll have to go back to the old design.

 

[snowygrouch 1]

Kristen,

You can print the brackets without support. It just means a little cleaning with a knife one one end afterwards

but essentially its ok with no support. Print it so that the end that goes onto the motor face is downwards, and turn

off support.

Even if you decide to use support, I dont see why you should have any particular issue.

Sorry but I dont have time to go and dig out old designs....

C.