Worn & eaten belts / bent Motor mount

[dstorer7]

Hello all,

I have read the posts here already and have a question which has not been answered (as I can tell). My machine is a Rostock Max v3. I have been dialing this bad boy in since I made it in Octobr/November last year, and opened it up to adjust the top assembly so the T-slots all have the same length (something not mentioned in the assembly Wiki) and found a lot of rubber particles from the belts...

Well, it (obviously) looks like I over torqued the belt(s) and the right side is getting eaten by the stepper's timing pulley. All of the belts had the same (general) note when plucked. This is the worst one, but I have this in some form on all of the belts. So I have to purchase new belts - the first question is the quality of the belt from SeeMeCNC(SMC). Are they a standard belt for normal use or is there a better manufactured brand (professional grade) that I should look for? I'm not looking to circumvent the SMC guys, I come from the 'Belt & Suspenders thought tank' and like to fix things once and have it be a maintenance issue with long running times in between.

Here you can see the Injection-molded motor mount is bent. Even with the alignment slots in the top melamine panel, I imagine that I will still have my belt wearing issue due the the cant now present in the motor mount. I have been to the SeeMeCNC site looking for replacement mounts but they don't seem to have them available. Has anyone come up with a solution to replace / purchase stiffer mounts?

Thanks in Advance...

[rootboy]

The first thing that comes to mind is to take the drawing of the mounts to a machine shop and have replacements made in aluminum. If I went that route, I would take the two plates (mounting plates in my mind) as a reference, and "fill them out" by making a one-piece box mount that included both the inner and outer plates and the slot for attaching to the verticals. Add a couple of mounting holes on the inside part of the new mount, and you've stiffened up your vertical as well as keeping this from happening again.

Me, being not so much a cheapskate as someone who doesn't mind making a field mod to his machine, I would take the mounts out and gently heat them up on a hot plate to get the bend out, and put them back in with a new supporting block on the far end of the mount screwed to the base to keep the mount from bending in again.

As to your belts, this is what I chose to go with since they have wires in the belts which should prolong their life:

https://www.amazon.com/gp/product/B0777 ... UTF8&psc=1

[geneb]

That's some epic over-tightening there, Lou.

The length of the t-slot isn't really that important - the critical dimension is the distance from the top of the bottom assembly to the bottom of the top assembly. That's why there are stop-screws installed to make sure that the distance is easily set.

Trying to repair that bent glass-filled nylon part really isn't practical.

If you tighten the belt so much that you can get a note out of it, it's probably too tight. You want it tight enough that there's no visible "slop" when you manually move the carriage back and forth.

g.

[dstorer7]

Thanks for the replies!

Rootboy: I appreciate the suggestion for belts, they are not available, so I'll keep looking... And I don't have enough $$ to get new mounts hogged from bar/billet stock, so I'll see if I can get new original ones through SeeMeCnc and less torquing. If I had my enclosure done, I'd buy a steel nozzle and try printing new ones from carbon fiber using the models from Github.

Geneb: Thanks as well. The distance instruction is not mentioned at all in the build wiki, I found that pearl from rooting thru the forums, etc. I busted the top apart to loosen the stepper motors to adjust the distance since my X tower was 1/16" longer that the other towers, and then I found all the rubber shavings and the bent mounts. So I posted about making sure the towers are plumb to the base and the importance of the same distance between the Top of the Base Assembly and the Bottom of the Top Assembly at each tower. I hope that will help others that buy the DIY kit. I read somewhere about the belt emitting a note when plucked, but that was some other design and I have learned a big lesson (which is normally how I/we learn...). I also received your zendesk email and look forward to hearing from your colleague about replacement parts.

[geneb]

Apparently my reading comprehension skill was on vacation when I first read your post - it didn't register that you had different length extrusions, which is really an annoying problem. I'd recommend you shim the towers at the top to make them match the X tower - you want the top to be completely parallel with the bottom.

I wouldn't worry about the belts - the mechanical load isn't anywhere near high enough to justify the cost of the extra-strength version.

g.

[dstorer7]

Sounds better than just relying on the screws to do their job. Will look get that done - Thanks.

[rootboy]

"I wouldn't worry about the belts - the mechanical load isn't anywhere near high enough to justify the cost of the extra-strength version. "

Times must be tough around your parts, it goes for $3.85 on eBay.

https://www.ebay.com/itm/5m-PU-With-Ste ... Swuk1ZzG4Q

"Rootboy: I appreciate the suggestion for belts, they are not available, so I'll keep looking... And I don't have enough $$ to get new mounts hogged from bar/billet stock, so I'll see if I can get new original ones through SeeMeCnc and less torquing. If I had my enclosure done, I'd buy a steel nozzle and try printing new ones from carbon fiber using the models from Github."

If you can get the original parts that would be best. If not, I would have two side plates cut out with spacers to hold them apart, rather than a one-piece design. But I didn't explain that well in my first post.

[dstorer7]

Hey Rootboy,

Thanks again. I contacted SeeMeCnc(SMC) customer service and they are doing me an huge solid by sending me new injection molded mounts. So one good turn deserves another, I bought new belts from them. I appreciate all your help and the next time around (which I hope will not happen for quite some time) I'll look to get the better belts. I am in 'serious like' for SMC and their customer support.

Lesson learned, I'll set them up as advised by geneb.

[rootboy]

Great news!

I think that with less tension, and proper alignment, your belts will last nearly an eternity. My belts were not in bad shape at all, and I only replaced them because I was upgrading my motors. I have kept them as spares in case the need arises.