Nema 23 Questions

deckingman

Yes, I am familiar with the belt setup. My printer started as a Tevo Tarantula which was belt driven. I think I am still using two pieces of the original frame for my spool holder. Everything else has been replaced.

I did quite a bit of research before adopting the threaded rods. Everything I read about belt driven systems seemed to emphasize things like stretched belts and skipping teeth under load. I suspect now, that what I read was produced by the threaded rod companies.

I have been thinking about returning to belts. It seems like a good exercise in simplicity. Your comments on inertia and backlash are supported by experience.

Take a look at these. I find them hard to resist :). Anything used in medical ought to be smooth and accurate, I would think.

https://www.thomsonlinear.com/downloads/actuators/Stepper_Motor_Linear_Actuators_bren.pdf?utm_term=Download the new brochure %2526gt%3B&utm_campaign=How can you reduce design and assembly times&utm_content=email&utm_source=Act-On+Software&utm_medium=email
regards,
Tim

The trouble with forums is that they are populated by armchair engineers who read something (usually posted by someone else) which may be relevant to a 30 tonne metal shaping machine, and assume that it must me relevant to a small 3D printer for no other reason than it also has an axis that has linear motion.

Ditch the screws. Use timing belts. Timing belts don't stretch because their function is not to stretch and that is what they are designed for (the exception being imitations that come from parts of the world where people tend to be small and have funny shaped eyes).

I didn't realise that you were trying to use screws for X and Y motion. Forget that spread sheet and those calculations - they are not relevant to screw driven axes.

I haven't read the specs but the actuators you linked to will likely by too slow and have too limited travel for application in a 3D printer. Being "medical" they'll likely cost a fortune too (but I guess they'd be hygienic and won't contain nuts).

wilriker

@deckingman said in Nema 23 Questions:

(but I guess they'd be hygienic and won't contain nuts).

I'd rather say they either drive you nuts or have to ability to cure you from that state.

deckingman

@wilriker I should have said that being "medical" they'll likely cost an arm and leg but you need to be a native English speaker to understand that.

wilriker

@deckingman Now I feel confused (in my national identity) because I understand it but cannot find the German equivalent in my head right now.

TimVukman

Hi:

I haven't left, I was just busy rebuilding the printer again.

So, to the important part first.
ein Arm und ein Bein according to google translate, which does not understand context or nuances:) For all I know, the saying may not even be used in German. I find other languages challenging since they seem to have a whole different word for everything!:)

I removed my Y axis. It was never as solid as I wanted it to be. I build another box out of extruded 20 x 40 V-Slot and put a linear slide bearing on each one, I have a carriage plate spanning the two rails. On the carriage plate, I have two (one at each end - front and back) bronze threaded bearings that the lead screw goes through.

The hot bed is mounted to two rails mounted to the carriage plate. It is a very solid assembly with excellent movement. I went back to the Nema 17 motor and changed the config.g setting back to what they were before the Nema 23.

I printed an almost perfect configuration cube. (the corners aren't perfectly square and I know I have some play in the X axis.

Having said and done all that, I think that I am going to replace the threaded rod with belts. Physics clearly implies that belts would be smoother and provide less resistance to motion. So, I have seen pulley ends with 16 teeth, 20 teeth, etc. Is the number of teeth important? What about belt size?

This just never ends I was printing something last night, and I received a heater fault message. I now get a constant 2000 degree reading on the hot end heater. Shouldn't be too hard to figure out.
Thanks
Tim

deckingman

@timvukman said in Nema 23 Questions:

So, I have seen pulley ends with 16 teeth, 20 teeth, etc. Is the number of teeth important? What about belt size?

This just never ends I was printing something last night, and I received a heater fault message. I now get a constant 2000 degree reading on the hot end heater. Shouldn't be too hard to figure out.
Thanks
Tim

Pulley diameter doesn't matter too much IMO. I prefer 20 teeth as the bend radius is a but less and they seem to be more commonly available. If you do the maths, 20 tooth on a gt2 belt is 40mm per revolution so you get 5 full steps per mm (one full step is 0.2mm). With a 16 tooth pulley it's 32mm per revolution so one full step is 0.16mm which is a bit of an odd number. But in either case, for resolutions less than 0.2mm, you have to rely on micro-stepping for accuracy so not much to choose between them.

6mm wide belt is fine. I use it to throw 3Kgs around at highish speed, so for your printer it'll be perfectly OK.

2,000 degree C usually means something is open circuit (e.g. bad crimp or broken wire)

TimVukman

Thanks
I shall start understanding what I have in my collection of pulleys.

I replaced the entire extruder with a new E3d V6 that I had just received. This one did not have a plastic tube in so it jammed up on me. I now have the tube all the way in and it is extruding. It's making a mess which I would normally say is over extruding, but it is using the same bowden as the previous one which was laying down nice lines.

More investigation required, I guess, but not heater error anymore.
Tim

wilriker

@deckingman said in Nema 23 Questions:

6mm wide belt is fine. I use it to throw 3Kgs around at highish speed, so for your printer it'll be perfectly OK.

And I'd say go for genuine Gates from the start (I failed at that). They are not that much more expensive than the Chinese knock-offs but will definitely be better quality. You can search for GATES PowerGrip GT3 xxx-2MGT3-6 where the xxx is usually a length in mm. They seem to only come in closed loops (as far as what I have found) but you can of course cut them to what you need. For the longest one I found so far with 1830mm I would have to pay a little less than 9 € plus shipping - 2m Chinese belt usually cost around 3 € (admittedly including shipping) so not reason to go with the cheaper ones unless you need 10s of meters of belt.

And don't worry that they are called GT3 - this is just the new product generation and fully compatible to GT2.

TimVukman

@wilriker said in Nema 23 Questions:

GATES PowerGrip GT3 xxx-2MGT3-6

Thanks for the info. I found them on Amazon.ca, but not sure it I have length choices. Getting stuff from the UK takes almost as long as China. I haven't checked the US yet.

Since I changed out the whole hot end, I will need to recalibrate the bowden extruder by the look of the prints. What would be a good hot end? It seems the E3d V6 is touchy to get the flow set up. There are so many choices that it's hard for my level of experience to make a choice.
Thanks

deckingman

@timvukman Personally I'd go for the lite version of the V6 unless you really want to run higher than about 235degC. It has a PTFE liner which goes right through the heat sink and is much less prone to jamming. If you already have a V6, then I think you only need but the heat sink (and some PTFE tubing).

wilriker

@timvukman As it usually is: while researching for where I can buy them in/from Germany at the lowest price I was stumbling across a Canadian shop also. But for the life of me I cannot find it anymore.

TimVukman

Hi wilriker:

I did find the home site for gates belts, and I found a ton of automotive belts. I did see indications that the size I was searching for existed. I did not find it though.

In the meantime, today I switched my X and Y drives back to belts, and each is running on a linear bearing instead of wheels. I found the original belts and though I had to extend them, they are installed and tight enough that there is no skipping.

Currently printing a 20mm cube that looks fantastic. I missed the step of changing the 500mm/sec for the threaded rod down to the 100mm/sec for belts. Very smooth!

I used the extruder bar on the web interface and turned it down to 80%. Not getting the splotches of filament anymore.

Thanks so much for the assistance and suggestions. Very happy. I will find the Gates belts. Gorilla Super Glue works very well for extending belts. Just cut off a section and apply the glue so the teeth of one part mesh to the teeth of the next part. Then glue the last part back on teeth to teeth and leave the backward section inside the V-Slot.

Phaedrux

@wilriker said in Nema 23 Questions:

@timvukman As it usually is: while researching for where I can buy them in/from Germany at the lowest price I was stumbling across a Canadian shop also. But for the life of me I cannot find it anymore.

There's only so many places in Canada to get printer stuff.

spool3D.ca
Makerparts.ca (openbuilds distributer)
Filaments.ca

wilriker

@phaedrux said in Nema 23 Questions:

There's only so many places in Canada to get printer stuff.

I cannot comment on that but as @TimVukman pointed out Gates belts are mostly used in automotive and I guess there are more shops based in Canada to get these kinds of parts.

deckingman

@timvukman I've been using generic (non-Gates) belts for many years and never had a problem. That's moving a very heavy print head (around 1.5 Kgs) around at high speeds and accelerations. Other users, on other forums have reported that they can't really tell any difference between generic and Gates belts in terms of any print artefacts. I'm not saying that all generic belts are good and maybe there are some cheap Chinese ones around that have issues, but I've never come across any in my own personal experience.

TimVukman

@phaedrux

Thanks for the Canadian distributor list. I have not dealt with Filamensts.ca yet. I'll go check out the products they carry.

Tim
edited to fix spelling

TimVukman

@deckingman

Thanks. Good to know feedback. I'm not sure how much use one would have to have to stretch them. I would think that it would take a while. I know from cutting mine that there is a layer of fiber inside the belt for reinforcement, so it may last quite some time without issue.

TimVukman

@deckingman
Sorry, I missed this in the bunch that came in since I last checked the board. Thanks, that's the one I ordered!

deckingman

@timvukman Yes. They are timing belts. Their function is not to stretch.

I've read several of posts on various forums from people who have tried steel cored belts, thinking that they would be better from a stretching point of view. Then they fail because the steel cores break through being bent around a small pulley, the straightened, then bent - etc etc. Then when the steel core breaks, thee is no support for the rubber so the belt stretches which completely defeats the object of having steel cores.

I think its the tooth profile and what the teeth are made of that is the important thing. If these aren't right, they will wear because of the bad material itself, or because the teeth don't mesh properly with the pulley. If there is a build up of black dust around the pulleys, that's a good indication that something is amiss.

Having said all that, I consider belts to be consumable items which should be replaced periodically - just as one replaces can belts on cars.

Phaedrux

@timvukman said in Nema 23 Questions:

@phaedrux

Thanks for the Canadian distributor list. I have not dealt with Filamensts.ca yet. I'll go check out the products they carry.

Tim
edited to fix spelling

They have a lot of harder to find specialty stuff. And the house brand they use is pretty decent.