Hoss 4th axis material list questions

[seanreit]

I don't have the spare lathe sitting around that Hoss had.

Can someone point me in the direction of the spindle, bearings and other materials such as jaws, and gears so that I can make one?

I have a CNC mill to do the aluminum parts, but I want to make a system just like what he has.

I think I can find the DC motor on ebay for the high speed part, but I don't know where to get the gears and belts.

Sorry if this has been discussed before, I could not find it, so if you remember reading a detailed thread, please post a link.

Thanks in advance,

[The Blight]

http://littlemachineshop.com/ has most of the stuff you need.

[seanreit]

I went to that site, there are more than one spindle, which plate would you recommend. I want a setup as close to Hoss as I can get. Obviously I will have to build my own control panel, adapter plates etc. I'm not proficient in the mechanical parts / gears/ bearings. I only have about 7 inches in Z, so need a smaller plate/ chuck. Is there one you have in mind? Should I just call them?

[hoss2006]

SDP/SI is where I got the timing belts and pulleys.

Just search for these part #'s.

A 6A 3-15DF02508 .200 (XL) Pitch, 15 Teeth, Aluminum Alloy Timing Pulley
A 6A 3-27NF03710 .200 (XL) Pitch, 27 Teeth, Aluminum Alloy Timing Pulley
A 6B 3-060037 .200" (XL) Pitch, 60 Teeth, 3/8" Wide, Urethane Belt

You can get the whole lathe head assembly from LMS for $99.
The timing pulley will have to be bored out to fit the spindle to replace the stock gear.
The 3 in. 3 jaw is the original chuck with the lathe.
Hoss

[seanreit]

Thank you Hoss,

Any advantage to making your own spindle holder? I can't tell from any of your pictures how you are mounting to the table, I see no screws at all!

Also, I can't tell what this is highlighted in the attached.

[hoss2006]

The advantage was a little weight savings but it's not the much.
It's bolted from underneath to the 3 x 22 steel plate which is then bolted to the table,
you can see a couple 3/8 socket heads if you look close.
The pic is just a block that the long 1/4-20 socket screw pushes against to adjust the belt tension.
Hoss

[jalessi]

Hoss,

What is the max rpm the 4th can rotate using the stepper motor only?

How accurate is it, can it hold .0005 ?

I would like to be able to have a max rpm speed of 500 rpm, can it be done using only a stepper, I dont want to have two motors?

Thank You

Jeff Alessi
jalessi@aol.com

[seanreit]

Originally Posted by hoss2006 The timing pulley will have to be bored out to fit the spindle to replace the stock gear. Hoss

So what did you do, mill the grooves into the spindle? I don't see a gear attached to the spindle. What's the black cap on the spindle?

[hoss2006]

Originally Posted by jalessi Hoss, What is the max rpm the 4th can rotate using the stepper motor only? How accurate is it, can it hold .0005 ? I would like to be able to have a max rpm speed of 500 rpm, can it be done using only a stepper, I dont want to have two motors? Thank You Jeff Alessi jalessi@aol.com

I think a stepper can run at 500 rpm if the voltage is high enough but you lose torque the higher you go.
A servo motor would be the way to go to get high rpm and positioning control with one motor.
We figured out the positioning accuracy once and depending on the microstepping, it was around .0002 (in theory).

[hoss2006]

Originally Posted by seanreit So what did you do, mill the grooves into the spindle? I don't see a gear attached to the spindle. What's the black cap on the spindle?

Actually I just flipped the belt over to run the flat side with the lathe motor.
Made a smooth pulley for the motor and swapped the spindle spacer and the
timing pulley.
The 4th axis needed the timing pulley closer to the head to line up with the stepper
and I didn't feel like moving the lathe motor over to match up.
Could have added a spacer to move the stepper mount out farther to line up
with the original position but that's too much like work.
I think the black ring is just one of the spindle jam nuts.
Hoss

[jalessi]

Hoss,

I have several servo's, using one is not a issue.

Do you think 3 to 1 drive ratio would be ok?

I have to find out what encoder would be best for this aplication.

I am guessing a higher engaged tooth count would be better, do you have any suggested pulley specs?

Thank you

Jeff Alessi
jalessi@aol.com

[hoss2006]

The pulley ratio would depend on the max rpm of your servo.
If it's only 2000 rpm then a 1:1 would be best.
That would give a nice finish on any parts you would turn.
An MXL .080 pitch pulley would give a lot more teeth per pulley.
Hoss