Jump to content
Ultimaker Community of 3D Printing Experts
meduza

Meduzas "bolt-on" belt geared feeder upgrade for UM2

Recommended Posts

I have been thinking a lot about making a bolt-on upgrade for the UM2 with a belt-drive, that would increase the pushing power, and also remove the thermal coupling between the feeder motor and the knurled bolt, since it has been shown that excessive temperatures at the bolt can decrease the performance of the feeder.

I did a few sketches during the last year, even did a printed mock-up that i posted on the old forum, but never got around to completing it. Yesterday i sat down and did a redesign in CAD, printed the pieces and now decided to post it here on the forums for your feedback :)

It is a very simple construction with a minimal BOM, only two GT2 pulleys (one 20T and one 36T), a 110mm long GT2 belt loop (55T), a 5x40mm cylindrical pin, two MF695 flanged bearings, some M3 screws & nuts and a few printed parts. Total cost should only be about 15€ says a quick look at eBay prices.

It functions as a gearbox that moves the knurled bolt a few centimeters outwards and upwards, and provides a new nema17 hole pattern which means that it will work with any feeder that is designed for the standard feeder position at the UM2, including the @IRobertI feeder and the original UM2 feeder, it gives you a gearing of 1.8:1 and removes almost all thermal coupling between the motor and the knurled bolt.

The only change needed to use this geared feeder upgrade is to change steps per mm in Marlin to the original value times 1.8, thats it!

All STL's and BOM: https://www.youmagine.com/designs/belt-geared-um2-feeder-upgrade

CAD Pictures:

5a33103447de4_2015-08-1214_22_55-AutodeskFusion360.thumb.png.b98eb1f1cbbda25a913435d134b2fe1c.png

5a33103489b74_2015-08-1214_23_10-AutodeskFusion360.thumb.png.132e6569013b0e34b5d70852813719fa.png

5a331035014f9_2015-08-1214_23_39-AutodeskFusion360.thumb.png.facfdfffe9a53c76149ec588947263ad.png

5a3310352825e_2015-08-1214_24_19-AutodeskFusion360.thumb.png.4967ac2fc307fa9d8d1c320db708cc67.png

Photos:

5a3310358c5d6_2015-08-1215_38_18.thumb.jpg.e58d6ae3f9737846a733f93191d11c1c.jpg

5a331035b048a_2015-08-1215_43_44.thumb.jpg.3a2856c9a2b991f4e14c0ac9f1991ce1.jpg

So, what do you guys think about it?

5a33103447de4_2015-08-1214_22_55-AutodeskFusion360.thumb.png.b98eb1f1cbbda25a913435d134b2fe1c.png

5a33103489b74_2015-08-1214_23_10-AutodeskFusion360.thumb.png.132e6569013b0e34b5d70852813719fa.png

5a331035014f9_2015-08-1214_23_39-AutodeskFusion360.thumb.png.facfdfffe9a53c76149ec588947263ad.png

5a3310352825e_2015-08-1214_24_19-AutodeskFusion360.thumb.png.4967ac2fc307fa9d8d1c320db708cc67.png

5a3310358c5d6_2015-08-1215_38_18.thumb.jpg.e58d6ae3f9737846a733f93191d11c1c.jpg

5a331035b048a_2015-08-1215_43_44.thumb.jpg.3a2856c9a2b991f4e14c0ac9f1991ce1.jpg

Edited by Guest
  • Like 9

Share this post


Link to post
Share on other sites

The backlash of the curvilinear GT2 tooth profile is very low by design, and since there are quite many teeths in engagement (actually about 50% of the teeths are in engagement at any given time) on a very short belt, i do not expect backlash to be a very significant factor at all, especially since the gearing reduces the impact of backlash even further.

Belt tension is very easy to adjust for, if it ever would become a problem.

Edited by Guest

Share this post


Link to post
Share on other sites

Okay, couple of questions from me, since I've never modified the firmware before:

1) If I compile the source from https://github.com/Ultimaker/Ultimaker2Marlin without alterations, this will compile a default UM2 firmware, correct?

2) Assuming no other alterations required from above, what settings do I actually modify to change the step rate for the extruder?

Share this post


Link to post
Share on other sites

Setting the steps/mm through g-code appears to work as expected.  Did an extrusion test and got decent results (I've never been able to go above 6 mm^/s without a total print failure, but this went all the way to 10 mm^3/s, but with noticeable under-extrusion issues starting halfway through 7 mm^3/s), but I'm going to do some more fine tuning on this.  I don't think I got the belt lined up perfectly.

Edited by Guest

Share this post


Link to post
Share on other sites

Biggest problem I ran into is that I use @IRobertI's feeder design in conjunction with his low friction spool holder design. The casing for the new extruder pushes the feeder out just far enough that the screw prevents a spool from being mounted on the low friction spool holder.

I'm temporarily using the stock spool holder while working on a mount design for the low friction spool holder that mounts the spool holder using the unused NEMA hole pattern on the opposite end of the machine. Making a few final tweaks to that design and once it is mounted and working, I'll post the STLs here for others to use, if they wish.

Share this post


Link to post
Share on other sites

I was starting to assemble the stuff but my 5x40mm pins can't fit the bearing or pulleys. I bough this http://pages.ebay.com/link/?nav=item.view&alt=web&id=361324052257&globalID

So that doesn't work. Can I use a simple m5x45 screw? Or anyone could paste a sample of what to buy on ebay so I can search something alike that could really work?

Share this post


Link to post
Share on other sites

I did try that, but they are freaking hard. I tryed putting it inside the drill agaist a metal file, and after 10mins, it still didn't fit in. Really really hard little pin. I suppose if I do it for 30mins I would make it, but my idea was to make 4 extruders... I would prefer to just buy the correct stuff.

Share this post


Link to post
Share on other sites

The pins i used (had them at home, dont know the source) did work right out of the box with no sanding, it surely was tight but i did not need too much pressure to fit the bearings to the shaft.

@neotko, it sounds like you have got hardened pins, those are as hard as the file so thats why almost nothing happens. You can soften it by using a small gas burner to heat it to red hot and let it cool in air.

A M5 screw is not that good of an option, i would look for a piece of silver steel rod (a good hardware store) or just a 5mm stainless steel shaft (hobby/rc stores can be a local source), both can also be bought on ebay.

  • Like 1

Share this post


Link to post
Share on other sites

Well @meduza I just bough the perfect (imo) product for the 5mm shafts.

This are Axis 5mm for Motor Emax GT3520 and I bought them on a R/C Hobbies shop for 1,34€ each (so really nice) they fit perfectly on the bearings and gt2 pulleys, the fit it's just perfect, smooth and without any hard or easy slippery. So finally I'll be able to assemble the feeder upgrade this week.

IMG_6631.thumb.JPG.13f797d56022bafe0b9cb4dc18924d58.JPG

Also imo they are perfect since they are (edit) 60mm+ long and I wanted to add a 8mm/5mm coupler to purge the feeder manually. There are also 50.5mm long versions but they where 3,50€ each.

IMG_6631.thumb.JPG.13f797d56022bafe0b9cb4dc18924d58.JPG

Edited by Guest

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

Terms of Use Privacy Policy