Beltless Drive X-Y Axis (Level 2 - Techie) (Page 4 of 5)

http://www.ebay.com/itm/100M-1000M-Moss … 3a87b2299c

Quite a bit more $ than buying from China but if you want to use a USA based reseller I got mine here... http://www.ebay.com/itm/350252467175?ss … 1497.l2649

My 3DR Delta uses Spectra instead of belts and as noted once it gets past the initial stretching and you take up the slack it pretty much stays that way. That said I still prefer GT2 pulleys and belts, they seem to be a bit more precise IMO, or at least I've yet to be able to duplicate the outstanding print quality of my GT2 upgraded SD3 on the Delta machine. The GT2 upgrade is however considerably more $$$ than a roll of Spectra...

Just pm me with your address. You use paypal?

So I upgraded, and I wanted to note I had to change my steps/mm on x and y to 91 (maybe 92, I'm testing a print atm), where they were 88 before. 4% change. I kept the same pulleys of course (or else this would not be noteworthy.)

I am not certain what may have caused this [a couple undecided thoughts.]  But it seems otherwise like a beautiful upgrade. It astounds me how functional a few wraps are. It was a bit of a pain to string the first time, though. I strung the y axis the wrong' way (upside down) and found the second time it was much faster to restring.

Hi Ward,

I suspect the Estep info was wrong. I should not have changed it. I thought I had to change because I was doing nickel tests and i've always had my interior holes to be smaller than they're supposed to be.  This even includes the rectangular holes in that test. I scaled to make that test work, but eventually had to scale down again because I care more about exterior diameters. I am right now somewhere close to the original 88 steps that it had. I think maybe at 89, and that could be that I was always off calibration, perhaps.

Hmm, I hope my spectra doesnt stretch more more. I am running out of tightening room. I also am not certain how tight I should have it and might have gone a bit overboard (but at least I have bearings everywhere so the load is not a problem.)

In the future I'll use a nicer type of attachment for the spectra lines. I ended up looking my adjustable printed spectra line pieces, and used some special cone type m3 washers. Sorry that's a little vague.

Do you know the pound strength of your original spectra? it varies. I actually have possibly off-brand spectra, the line that robotdigg sells.

I also have more Z-wobble than I've had in the past. but unfortunately its hard to isolate the source since I made many changes at once. I upgraded to a M6 1mm pitch rod which is about 40% finer pitch than the stock setup.  However it could also be overshoot or stretch, and not Z-wobble. I'm still working that out.

yeah I need to get a dial indicator. One investment I haven't made yet. Plenty of calipers, no dial indicator though. So i have to calibrate with printing objects.

That said, I think assuming the e-steps would stay the same is a fairly reasonable assumption. What has changes? The same pulleys are being used.

Pulleys are based upon diameter. In this case, you have to look at the interface of the belt/line with the pulley. The line has a much smaller thickness so interfaces almost directly with the teeth of the pulley. That is the diameter to determine linear translation. The belt is much thicker. But in this case, the belt sinks into the pulley teeth. Most belts used for linear motion have a re-inforced section that does not stretch, this is usually some cord material. Where this corded layer is in the belt is the how you determine the diameter interface to the pulley. In our case, the difference between the belts corded layer and using spectra line is almost the same and should be negligible.

d of spectra might be thinner than what you measure freestanding, because on the pulley it's quite tight and a bit compressed (since it wraps around the pulley). It might not make a difference. I'm going to go measure it to see if I can get anything meaningful. Unfortunately I don't have a micrometer, just calipers.

Fishing line has been typically used with Lawsy's carriages and those had bolts that were used for the adjustment right on the carriage.  Just tie the line to the bolt head and tighten.  If you have an SD4 and want to use the existing carriages you will have to get creative as to how to attach the line to the carriage.  Then just use the front idler adjustments to tighten the line.

Oh, 3 wraps around the drive pulley and it won't slip

Yep that simple but it needs to be tight.

I have not had any noticeable wear on the pulleys and yes the line does float side to side on the pulleys a little bit.
If you are going to use the existing carriage you will have to figure a way to attach the line to the carriage on each side.  Maybe you could drill a hole in the carriage somewhere and put a bolt through it or a screw into it.  I just don't know without having one it front of me but I would guess there is a way.