Plasma cutter advice please!

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06 Dec 2023 19:50 - 06 Dec 2023 19:51 #287380 by oddwick
those are real nice looking profiles. on my ballscrew machines, i run the screws behind the gantry because it keeps it shielded a bit better from dust and debris.

@tommylight has me sold on the belts. i am sticking with 3m belts just because i have a ton of spare pulleys and belts so that will keep cost down.

i have this a little bit on the backburner because i have been wiring the control box for my 4080 router right now. i have been stuck on the design and decided to let it rest a bit to think on it. i am torn right now as to whether i want to mount the y motors to the frame and run a looped belt or mount the motors to the gantry and r/p the belts. these motors are nema 23s, but they are pretty heavy and i was trying to limit the mass that i would be swinging around. the entire gantry will be aluminum so that helps a bit but i was undecided which route to take. more belts and pulleys vs more weight. thoughts tom?
Last edit: 06 Dec 2023 19:51 by oddwick.
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06 Dec 2023 20:43 #287386 by tommylight
2.5 meters of belt will flex a bit, 5 meters will flex a lot.
So it is a balancing act, does half the belt with motors on flex more than full length belt without them
15mm wide, i would give it a try for sure, 20mm wide or above go for double.
If going double, adding an idler in the middle of the free belt should dampen the vibrations a lot.

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07 Dec 2023 11:51 #287435 by vre
Replied by vre on topic Plasma cutter advice please!
belt will 5m in total but each side of loop will be 2.5m.
In my laser engraver i have 1.6m travel (3.2m total ) 15mm wide on x axis htd3m and flexes a little bit for this reason am think to get htd5m 30mm wide.

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07 Dec 2023 23:51 #287501 by oddwick

2.5 meters of belt will flex a bit, 5 meters will flex a lot.

how much flex are we talking about?  right now i am at 1.5m with near zero flex, but they are drum tight.  my main flex was onthe z axis because ithe way i designed it wasnt able to take the loads that i was subjecting it to.  positioning accuracy was ±0.05mm over 1.5m, so not bad there. 

so for a closed loop, it would be 3m give or take, but with only one idler at the opposite end.  with double y motors that would be 3m x2, and since there is no contact with the head, i would think the flex would be negligible for a plasma.  if i run with the motors on the gantry, i have that weight, but 1/2 of the belting.

what i am trying to figure out right now is how i want ot arrange the belts.  i will be using hdr20 linear rails and before the belts sat on the top of the y frame with the v wheels and i still would like to keep them more or less flush with the frame rather than floating in space.  what i have been possibly thinking would be to mount the motors vertically and run the belts under the railing which i will be mounting on the side of the frame rather than on top of it just for a bit more protection from dust and debris. but i am really not sure about that.  i am just going to play around with a few different configurations until i commit

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08 Dec 2023 10:19 #287514 by tommylight
Flex will depend on weight and acceleration, so hard to say.
Do a quick test by clamping the motor and idler to the frame and give it a run, should be enough to see how it behaves.

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08 Dec 2023 18:12 #287566 by vre
Replied by vre on topic Plasma cutter advice please!
something other for hgr20 linear rails because
it is not easy to find them in long length is it possible to join 2 rails
or this will destroy carriages ?

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08 Dec 2023 20:27 #287588 by tommylight
It is possible, a friend of mine did it in his workshop with hand tools, but it is very hard.
I have also seen several factory machines with prolonged HGR45 and they all had the cut at 45 degrees where they join.

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09 Dec 2023 13:51 #287656 by machinedude
I just bought a desk top engraving machine. I was surprised by how well the belt drives did. i was looking into more information on them and go figure it led me back to tommy :)
i think not all belts are made to the same quality standards. Gates makes some really good belts but they are really expensive. one thing i found out about Gates is that the 15mm wide belts don't come with the 2mm pitch and are in the 3mm pitch range. another thing is you have to buy 50ft at the least with the open ended belts. if you want to get into the steel corded belts i believe you have to move into the 5mm pitch range and it looks like that kind of belt starts @around $13 per foot.
GT2 is the way to go but it would be nice to find another manufacture that has a quality belt at a better price point ?

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09 Dec 2023 14:24 #287662 by tommylight
GT2 up to 10mm wide
HTD3 up to 30mm wide
HTD5 up to 60mm wide
Those are roughly what i concluded by using some of those, it is exaggerated a lot to be over the limits of tooth slipping.
PowGE in China makes good quality belts and pulleys, not cheap as the no name ones, but very worth the money.
I did test the 15mm wide HTD3 from PowGE stainless steel reinforced one by making a loop and hanging it to the ceiling and hanging all 86KG i had back then on it, it did not budge nor could i notice flexing.
BTW, there is steel and carbon fiber reinforced 10mm wide GT2 belt, had both types, the steel one is quite stiff so no small radius's with it as it will brake the wires.
As a side note, cutting the steel reinforced 10mm wide GT2 requires using both hands with very good wire cutters (WIHA and Knippex), gutting the above mentioned 15mm PowGE is only possible in small bites.
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09 Dec 2023 14:40 #287663 by machinedude
PowGe is one i was drawn too. they specialize in belts and the construction looked comparable to Gates. They have a GT2 belt in the 15mm width range with a 2mm pitch. but finding the hardware is limited. most of what you find is for 3d printing and for the 6mm width. i did find a belt and hardware kit but i have my doubts about the belt quality in that kit but it seems worth the price just for the hardware included that would work with the PowGe belt i found.

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