Tree Mill conversion Questions

[Flyinfool]

I have a Tree Mill model 2UVR that I would like to convert to CNC.
This machine is similar to the 9x42 Bridgeport’s, but not really a clone.
Has anyone ever converted one of these?
What are the pitfalls that I should watch for?

Other than the power required, is it realistic to move the whole knee for the Z-axis instead of the quill?

I already have suitable computers, software, and this mill. Is it realistic to do this conversion for around $2500?

I have searched several CNC forums for the Tree Mill and found nothing.

I purchased this mill with DRO and a pallet of tooling for $1000 7 years ago. The mill works great as a manual mill.
I knew then that it is an off brand, the mill and the DRO manufacturers are no longer in business, but I have sold $2000 worth of the tooling from the pallet and kept the best for myself.

[Al_The_Man]

Originally Posted by Flyinfool What are the pitfalls that I should watch for? Other than the power required, is it realistic to move the whole knee for the Z-axis instead of the quill? .

Keep in mind you should fit ball screw if it does not already have and in my opinion it is not practicle to Z axis the knee, which means you will have to fabricate a Ball screw Z axis, there have been previous threads in these forums on this.
Al.

[Cold Fusion]

Using the knee as a Z axis isn't a good idea. The large amount of weight will speed up the wear of the ways on the knee because it's doing a job it wasn't designed for. You are much better off driving the quill.

[Flyinfool]

The machine does not now have ball screws, but I do intend to add them. The x-axis screw is fairly worn and there is almost 1/4 turn of backlash right now.
I may go to ball screws even if I do not do the conversion right now.

The machine currently has a power drive for the X-axis built into the knee, this will all have to be disabled and removed for the conversion.

I have done many searches on this site for info on the Tree mill but have not come up with anything. I will do more searches.

I may start out with a 2-axis conversion till I can figure out a good way to gain access to the quill. The only part that is visible outside the casting is the spindle its self and both ends of the shaft that the feed handle is on. I may be able to use that with a gear reduction since there is 1.25 turns to get 3.625-inch quill travel.
I assume that I will need to add a spring to control the backlash between the shaft and the quill.
On the other hand, there is a power quill feed that could be used for an input point. The power feed input spins at spindle rpm and goes through a significant gear reduction so I would probably need to step up the servo speed and it will still move very slowly.
I do not have access to a second mill for doing any major modifications.

Sorry for being wordy but sometimes I just need to bounce ideas off of knowledgeable people for a sanity check.

Jeff

[Al_The_Man]

Originally Posted by Flyinfool On the other hand, there is a power quill feed that could be used for an input point. The power feed input spins at spindle rpm and goes through a significant gear reduction so I would probably need to step up the servo speed and it will still move very slowly.

A common way is to mount a ball screw parallel to the quill and mount a rigid bar connection between ballscrew and quill, is it possible to modify the existing power feed to accept a ballscrew setup by getting rid of the gearing etc?
Al.

[Flyinfool]

I just pried of the cover plate.
It looks like there is a stub of a shaft the can be accessed.
It currently has the worm gear on it, it looks to be just a roll pin holding it.
It takes ~29.5 turns of that shaft to cover the full range of 3.75 quill travel.
That equals 0.127 inch per rev (I will do closer measurements, its probably .125 per rev)
What are the chances of getting any realistic accuracy from that drive, possibly with just a coupling to the stepper and some sort of spring to control the backlash?

Jeff

[ViperTX]

Dan Maunch was doing a Tree CNC conversion....he has an advertisement in the classifieds for steppers....tweak him ...

[Flyinfool]

I checked with Dan, His was a refit of a mill that was CNC in an earlier life.

It looks like my only big issue will be the Z axis.
There are no exposed parts of the quill till it is about 1 inch down. That is where it just starts to show out the bottom of the head casting.
Even the depth setting is all internal.

It looks like direct coupling of a stepper to the shaft from the power feed may be my only access, short of cutting a slot in the front of the casting (the slot sounds like a real bad idea).

The return spring that is on the hand feed for the quill is just strong enough to couterbalance the quill, it will not raise the quill to the up position.

My thought was to see if I can make a new spring that would be strong enough to eliminate the backlash that is in the quill drive gears. It may make the quill dificult to use manually, but oh well.