Ah TENSHUN! belt tension guage by Pops668

Last crawled date: 2 years, 10 months ago

Tired of educated guesses for the tension on your printer belt?
Pluck the belt, listen to tone, measure the length, do the math.
Deflect the belt, measure the length, do the math.
Use custom tool of certain material, trust the result.
Cut belt to set length, engage tooth #3 from one end, tooth #4 on the other. Ooops, belt too short, cut another...
Or make a direct reading of force acting on the belt in Newtons.
If your printer can use a screw-type tension adjuster, it can use this tool!
Premise:
Idler pulley is subjected to belt tension x2; the belt makes a 180 at the idler (trig required for non-180 belt engagements!) so the tension for one belt is doubled on the idler.
Put a scale of some sort on the idler, divide the result by two.
Robert is your parents sibling.
The tool:
Spring loaded plunger, very basic 'Bass Scale' sort of thing.
In fact, stop now, buy a 'fish scale' (snicker, fish scale, fish-scale, puns) and do your own thing! Go nuts, I'll wait. Or not. Not your Dad. Could take him in a fight, probably. Will it rain later? What was I doing? Oh, yeah....
Springs harvested from printer bed. Don't know why printers ship with springs installed there, but hey, free springs.
Calibration is a breeze; 510 grams = 5 Newtons.
Hang increasing weights from the Adapter, mark on the Body where the Indicator lands.
Do this several times to make sure that gravity isn't fluctuating in your area.
The Indicator has two offset 'teeth' to better engage with the Springs...fiddle with the alignment when assembling the tool until it sits in the track right. Experience teaches.
The Indicator should be made from PETG or other tough plastic, as it acts like a safety device.
If your finger is in the Doughnut Region and the Adapter fails when the Shaft is snapping back, the Shaft could drive back into your bones.
Use:
Attach the tool to the tension adjust screw of the printer, and haul back on it to a value higher than what you want; this will free the adjustment nut. Loosen said nut.
Slack off on the tension to the desired amount, then carefully advance the nut to take up the free-play.
Don't tighten it! Just take up the slack.
Remove the tool, belt should now be very close to the desired tension, likely a little bit under due to the vagaries of taking up nut-slack.
The parts:
Body and Adapter are PLA, no supports.
Indicator is PETG.
Of flat M3 washers, two are needed. One at either end of the Spring stack.
One M3 nut, Acorn by name, Nylok by nature, is required on the Shaft.
4 Springs from [insert printer name here]...I used Mingda D3 Springs.
The Body is designed around 8mm Springs, you may want to modify it for other diameters.
Brass rod for shaft, 3mm or 1/8", M3 threads cut.
Buy a metric tap and die set; costs less than a roll of fancy printer-fodder, makes mechanical prints much more usable.
The Adapters are M3/M4, you may need M3/M3, I didn't need them, didn't model them, so I am not including them!
Can't think of anything else, signing off!
Pops668