Acme lead screws

Started by Rx7man, May 12, 2015, 12:57:56 PM

Rx7man

I took apart an old AFC, and I've been thinking really hard about how to drive it, so that it requires no modifications to the internals (so a DYI kit is possible)..

I came across this Acme Lead Screws and Nuts from SDP/SI  They didn't list any brass nuts for the 5/16th size, I'm thinking 5/16th x 8 double pitch would be about right... 1/4" per turn at 200 full steps/turn leaves you with better than .001" resolution when halfstepping the motor.

I'm looking for a couple other suppliers in the mean time
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

Rx7man

OK, those guys are out of the picture... Anyone who makes a screw and doesn't make the matching nut is stupid...

Trying these guys.. they have the nuts!, requested a quote, we'll see what they come up with

   PowerAC 5/16"-4 RS w/Bronze Nut | Nook Industries 
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

huh?

I think for V0.1 I'm going to tap a piece of 5/8th brass stock with a 1/2x13 (UNC) thread.. it'll perhaps act a little slower than I'd like being 13 turns per inch instead of 4 turns, but if it works it'll be a cheap start to the project.. I have enough things that are going to nickle and dime me as it is
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

#4


I was thinking maybe an electromagnetic plunger type, but probably a bad idea for sustained heat. But a tiny face stepper would be coolish, we need at max what 1inch of plungibility?
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

I had to trim the end of the AFC foot slider tube and still don't have an inch of travel.. let alone useful travel.  I think what I made on the lathe today will work OK as long as the thread isn't too fine.

I was thinking of a PWM controlled plunger, rather similar to the shutdown solenoid... Good part of it is if it fails, you have full power still, perhaps too much.. its reasonably easy to control, but my worry is you need a pretty strong one against the load.. it won't be under load MOST of the time though, only when someone mashes the throttle or when EGT's etc get too high.  Another downside to it is without feedback you don't know where it is, which means another analog input and TPS type sensor.

2 0 KG cm 6 Wire NEMA 17 Stepper Motor 42BYG228 | eBay is the stepper motor I'm looking at, I think it's plenty capable of doing what we're asking of it, especially if that Steed's fellow from the youtube vid had his working and that was considerably smaller.  I really want to stick with the 6/8 wire motors so I can get away from fullbridge drivers.  If we have 4 spare PWM output pins, we can drive them analog, and that would be the easiest way to reduce heat buildup in them.. just drive them at full power (255) while moving, then after it's been stopped for a while drive it at 1/4 power or so just to keep it indexed.
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

Rx7man

OK, so I got the quote back from Motion.. the 12" piece of lead screw is $26... OK, I can live with that..

EACH NUT IS $60!!!


Unless it just really doesn't work, I'm going to stay with my system!
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles

hakcenter

Welcome to the world of manufacturing, haha.

You want 10 prototype boards, that'll be 20$ ea. You want 20 boards ? $10 ea, you want 30 $9 ea.. hmmmm
TS2009 Deḇarim 8:2
"And you shall remember that יהוה your Elohim led you all the way these forty years in the wilderness, to humble you, prove you, to know what is in your heart, whether you guard His commands or not.

Rx7man

I have never been able to get 20 for the price of 10!

And speaking of that..  Mouser does typically have much better prices on single units, and their discounts ramp up quicker.. I didn't compare all the parts, but that's typically what I found.
'94 dually,  67/67 HE351VE, NV5600, ~600hp
'93 ECLB 47RH, new toy truck, H pump project, 1000hp goal, 300K miles
93 XCLB auto, bone stock, 350K miles
93 XCLB 5spd, bone stock, 100K miles