[Paraprop]

This is my first CNC project.

Yesterday I purchased from a second hand shop the X / Y table shown in enclosed pictures and a separate unit I think would make a great Z axis.

I would like to make a CNC mill out of it for maily mahining aluminum and steel.

Right now I cannot make up my mind on how to proceed.

I can see 2 possible solutions:

1. mount the Z axis onto the X/Y table and build another machining table in front of the X/Y table with the spindle mounted onto the Z axis and protruding onto the machining table.

2. Make a gantry for the Z axis and mount a machining table surface onto the X/Y table however the support is not very large consiering that the machining table may be 30" x 25".

Which way would you recomend to go and what are the issues to be considered

some additional data:

I measured the movements as follows:

X = 26"
Y = 20"
Z = 12"

for X & Y, I got 2 servo's included. They are Sanyo Denki Super U 80W, 75 V , 1.7A. Therefore I have ordered out 3 Gecko drives. But I am afraid these motors may not be strong enough for a milling application.

The servo on the Z axis was missing and I'll have to look out for one able to handle te spindle weight.
By the way, at the bottom of the Z ball screw, there is a brake mounted. It seems that it will release once 24VDC is applied to it. I haven't got 24 VDC to try but with 20 V, it did not release.

I have a DeskCNC controller waiting for this application. Not sure if it can handle suh a brake control on the Z axis.

[LeeWay]

Those are some fine looking parts you have there. Should do well with either type design I think.
XY looks beefy enough. Is the casting iron or aluminum? I am assuming also that we are looking at the bottom of the Y axis on top now?
The standard approach with the Z overhanging to the center of the table will have the obvious trouble of deflection if not built extremely rigid.
The bridge style would be a little easier to build rigidly I think. It is large enough that you won't be too concerned about part size.
Hard to tell from the photo, but the Z appears to less less beefy than the XY table. The bridge type is what I would go for.
I too am building a little mill and had to deal with the same question.
My Z is cast iron however and quite beefy in its own right. That lead me to the standard vertical mill form with a single column instead of the bridge.
I would like to build a bridge type as well one day. They are a little better balanced on cutting forces.
Good luck either way and I will keep watching your progress.
Congrats, BTW. Nice score.

[Paraprop]

Thanks for your comments.

Actually I was on the look for 3 large servo motors
of about 450 oz-in each at 3000 rpm for my planned Bridgeport Clone mill CNC retrofit when I stumbled on those parts. They seemed quiet well done and I decided to take them even it was not planned because I will not come across something like this very soon. ( I had no luck with my large servos though...)
Anyway, I was waiting to buy the clone mill after the machinery exhibition which will be hold from May 9th-13th only.


The XY frames are made of cast Aluminum.

The picture shows the unit the way I picked it up.
The X axis (longest axis) is at the bottom. The Y axis is on top. It is covered by another aluminum plate which is about 20 % smaller in size than the total possible working area. In this plate there are 4 holes for greasing of the roller bearings. That is why I thought it is on top.
However once you mentioned it, I think it is worthwhile to consider to put it the other way round. Would make sense.

While cleaning it today, I had to discover that the X ballscrew was corroded / rusty on a stretch of about 4-5" right half way. What a pity !!!
I cleaned it as well as I could with scotch brite and then sprayed it with WD40. Then I conneted a servo onto it and let it travel back and forth for a while. Seems much smoother now but I am not sure about the resulting accuracy and backlash it will have.

Really a pity to disover this issue because the entire material did cost me the equivalent of about $740.-

Z axis. You think the Z carriage is too week as ompared to the XY table ?
I have picked it up because of the strong Aluminum stand and the lead of the ballscrew is 5 TPI like the srews on the XY table and I do not have the time to go often to this place.

Tried the brake. Once energized with 24VDC it releases the ballscrew and I managed to get the carriage come down.

I am really wondering why they had such small servo's on this unit. I am afraid that they will not be big enough for my intended application, However I had them running only on 20 VDC and about 0.5-0.7 A. so to go to 1.7 A Therefore, there is still some improvement to expect.
Do you think the ratings on the servo motor plate stand for nominal ratings or for max. values ?

Sanyo Denki
Super U
Type U508-002WL3
80W, 75 V , 1.7A.
3000 rpm

optical incremental encoder 1000 p/r
type E5D1000C01B

I have applied 5V onto the encoder, It needs about 105 mA. This means, the Geckos will not be able to feed them and I need a separate supply.

I connected the outputs to a scope and the phase A square pulse signal reached not higher than 2.8 V whereas phase B reached 3.1V.
I ca't remember if this meats the TTL standard requirements so that thy will work with the Gecko's. Any experience on this issue ?


Below some more pictures.

[Paraprop]

In the meantime I got the 3 Geckos. yesterday I hooked the entire setup up on a small table. all the 3 servo's worked.

Now I need to understand how DeskCNC works and also to setup limit and home switches.

I got Omron Photomicrosensor's need to think about how to make a fail safe configuration with them.

Still thinking though on how to mount the Z axis on top of the X-Y table.

[9lrac9]

9lrac9 Here, This is why I love the zone... Be open with your ideas and every body will want to help or share ideas freely. You all have great ideas, and you could just about cnc anything. I know of a guy that can't afford much, his idea scale is way up there and he is working on converting a drill press to cnc. With a screw on chuck so he can use small end mills to mill parts. It's all possible... 9lrac9

[Paraprop]

Thanks to the great support I received from this forum, my CNC mill today ran the first time on all 3 axis.
I even already performed a 3D scan with it.

Had to increase the servo size for the X & Y axis though.
power supply is around 65 - 72 V

[LeeWay]

Looking good.
I see that you chose to keep it oriented as it originally was. Typically the long X axis is on top. This would have eliminated some of the need for way covers on that axis. Still though, as it is will be pretty useful. Most all the parts I do by hand now fit in a vise anyway. The long axis in X is rarely used by me in that case.
As it sits, it will be easy to install some way covers. A simple piece of rubber even a little oversized would work for both axes. Congrats and keep up the great stuff.

[Paraprop]

Hi,

have not got much personal advice fm. the forum but finally I am almost there...:wave:

Here my latest pics.

Further steps

Fitting VFD and large asynchronous motor controlled directly by DeskCNC PWM to 0-10V. converter.

Oiling system for linear guides and ball screws

Design a protection for the X & Y guides from dust and lubricant

provide lubricant system (supply and recovery)

tool changer ???