Denford Lathe Retrofit

[outback]

I'm in the process of retrofiting a Denford CNC lathe. I'll post my progress at it goes but first I have a quiestion.

I just built a nice 18" X 38" X 32" high stand for the lathe project. It is made of 2" square 80-20 extruded aluminum. My question is a 18 X 38 top for the stand. Should the lathe be mounted to a steel plate or could I use a sheet of 3/4" plywood or maybe two layers of plywood. If the top needs to be steel what should I use, 3/8, 1/2.....? The lathe bed and head weigh in at about 120LB,

Thanks,
Jim

[DICKEYBIRD]

Hi Jim, I'm really looking forward to seeing how you do your retro! I think a heavy gauge (13 or 14 ga?) sheet metal top with a couple braces under the lathe mounting points would work well for a top. Depends on what you have lying around. I'm sure there are some who will say nothing less than 1" plate will work.

For my Denford's new home, I modified an existing 36"L X 30"W X 36"H 2x4 wood frame I had under an old homemade CNC router . I covered the top with 1x6 tongue & groove pine with the grain going across the short dimension and added some diagonal braces to stiffen it up. The T&G locked in very nice and seems to be very sturdy.

I picked up a piece of black plastic carpet runner at Lowe's and covered the top with the grooves facing down to give a smooth surface for wiping up oil spills.

I'm using the original ORAC base to mount the lathe on and house the electrical stuff. The panel across the back provides a backsplash as well. It's real stout and has 2 rails running longways on the bottom that spreads the load across the wood table top. It looks and feels plenty sturdy.

The lathe will be pretty high off the ground but I did a few dry runs and it feels pretty good actually. I have to be careful with my back and I'll try it for a while as-is when I get it running. I can always shorten it if necessary.

[outback]

As of 11:30PM Sunday this is what I have done. Got a stand built for the lathe made from 80-20 aluminum. The base I bought from a friend that is heavy duty with wheels.

Below I'm making stepper motor mounts on a home built mill. I use this small mill more than I use my CNC Bridgeport. The sloted hole are to adjust the timming belt.


Here is the stand and the Stepper motors mounted.


Bed time,
Jim

[DICKEYBIRD]

Wow, you're moving right along there Jim. Those are some manly lookin' stepper motors you got there!

I'm curious to see what you're using for a spindle motor and how you mount it.

I'm still mired up with pesky paying jobs and haven't been able to do anything other than order parts and daydream.

ps: Got the contactors, thank you so much!

[DICKEYBIRD]

Oh yeah, did you find a source for the 10 groove Poly V/Micro V belts & sheaves to match the spindle?

I thought I'd got lucky Friday. I scrounged around work & found a Land Rover Disco alternator pulley & it looked perfect until I got it home & found out the groove spacing was wider than the J series Poly V @ 3/32".

What's the max spindle speed you're shooting for?

[outback]

Have a problem with the carriage stepper mtg. Does anyone have a pic or description of the original stepper mtg. I see the tapped holes in the lathe match the mtg holes on the stepper but how did they adjust the timing belt. I'm reluctant to slot the holes on the stepper motor. Did they have an idler pulley to tension the timing belt? What I'm doing now has several clearance issures. I have an idea brewing in my head how to resolve this issue but I don't wish to reinvent the wheel if there is no need to.
stepper mtg

The cross slide stepper mounted ok with my adjustment system. Still curious as the original techneque.
cross slide mtg

The spindle motor is orginal Denford.

Jim

[DICKEYBIRD]

The picture in the manual shows the mount plate attached to the stepper motor with the spacer tubes between it and the lathe body.

Maybe the bolts are smaller than the tube ID and the bolt holes in the stepper motor allowing a bit of wiggle room??

My NEMA 23 steppers are smaller than the 34 bolt pattern so I think I can mill slots in the mount plate allowing a bit of adjustment.

Hope this pic helps:

[outback]

What you show is kinda what I figured. They must use with wiggle room in the screws for tensioning. WOW. Well, at least I have a 100XL037 belt on order. I'll have the belt tomorrow.

The clearance holes in the stepper are for a #10 screw. I suppose I could use a #8 or #6 screw for more wiggle room. This could be easier than I thought.

Thanks for the diagram.
Jim

[DICKEYBIRD]

There probably wouldn't be much need for adjustment as those little belts are pretty darn stout and don't stretch.

I guess they built 'em to such close tolerances over there in northern England that the belts fit perfect from the get-go. Adjustment devices cost money and it's a well known fact that Yorkshiremen are pretty tight with a tuppence ha'penny.

[outback]

I had this idea on a timing belt tensioning adjustment so I had to go build it. If nothing else it will be easier to service the belt and stepper motor. It makes things kinda fall into place. Clearance issues resolved now.



Adjustable threads

Stepper Mtg

I'm rather impressed the Brits would build precise enough tension adjustments would not be required. It does make sense.

I'm ready to start wiring the control now. The VFD will be here tomorrow. This could proceed rather quickly now.

Milton, I would check with Motion Industries for that 10 groove pulley. I ended up buying the spindle motor from the guy in
Ann Arbor and the pulley was already on it. Glad I did now. Made life easier.
Jim