Converting an Excello to full CNC

[metron9]

I bought a nice Bridgeport mill from Techguy a couple of years ago and a nice little SB9 lathe last year and also built my own CNC machine using gecko stepper drivers and steppers using machIII.

I just bought this Excello machine tonight. It runs great but I aim to convert the air over hydraulics quill to a stepper motor control at least I think I should. All manuals included.

I don't have the machine installed yet but I am trying to figure out what to do with two Z access's. Should I think of the knee as a 4th access and should I completely remove the air over hydraulics system? I don't know at this point how it works mechanically, is it a worm gear, can a stepper be attached to that or directly to the quill gear shaft by removing the whole air/hyd system?


Some pointers on what to expect would help me sleep.

Stepper motors are 1100 oz each, I forgot to look at how many amps they need so not sure yet what I will need for a stepper driver or if i can tap into the existing drivers on the tape machine and control via machIII with an adapter of some sort.

The tool holders are #40 with the 1/2 twist lock. The rotating 12 inch table has never been used and has it's own stepper motor.

Just looking for some input. Thanks.

 

[metron9]

Picked up the Tape drive machine and the rotating table. I opened it up and the ball bearings were nice and clean. Poured oil in the cup perhaps 8 ounces, not sure how much oil one should put in this thing.
Turned the lovjoy by hand and the table turns nice. Wondering how the oil gets between the plate and the body though as it spins.

Also don't know what some of the allen head screws are for, one has a nut on it. Must be lock downs for the table but not sure.

Most of the tool holders are pretty worn, individual smaller diameter ones are just junk.
The 1-1/4 and 1" holders are pretty good, I want to find a 1-1/4 x 2inch shank for a ER 40 holder and collets. Unless someone makes a holder that fits this thing that has an er40 collet chuck. Meritool has 1-1/4 but they are 4" long.

Played with the paper punch machine a bit, that's a joke!

Initially it looks like I may use the existing 6 wire motors and wire them for 4 wire bipolar, not sure how much power I will have set up that way but I want to see if there are any problems moving the tables.

Should be here Thursday.

 

[metron9]

Got the mill today. Y axis is very nice, you can push the table from side to side very smooth. X axis has a problem, the bearing is mucked up but the table on the ways slides like butter almost rammed it into the back because it would not move before I removed the bearing from its mount. Checking prices for this bearing from the source but I may use back to back lower cost ones from VXB if they are too much$$$.

Z axes is not a ball screw but it rides smooth up and down, I rotated the motor using a wrench on the shaft that comes out the back.

Checked the table flatness from front to back using a v block on the table in 4 positions about a 9 inch circle with a .0005 indicator and it checked out to be about .001 . Very nice.

Using the beat up 1/2 inch collet and maritools er collet holder with a 1/8 .0002 indicator blank i get about .004 runout. Forgot to indicate the inside of the spindle though.

I will be removing the whole spindle drive mess and I am thinking of using a 20 to 1 gear reducer and stepper motor. that should give me about .001 per step. I measured roughly 4 inches for a full rotation. I have an old 60 to 1 that has a bad gear inside but it's only about 1/8 of the gear that is stripped so i could get 3 inches of spindle movement with that one and buy a new one once it proves itself to work well. Have not hooked up the motor yet but this weekend I expect to give it a spin.

Updated pictures-

http://www.practicalmachinist.com/vb/members/metron9/albums/excello/

 

[MLeonard]

Regarding the rotary table:

Also don't know what some of the allen head screws are for, one has a nut on it. Must be lock downs for the table but not sure.

From the location, I would guess they are for adjusting worm engagement, to minimize gear lash (hopefully without binding it up entirely).

 

[metron9]

Thanks Mlenard, I have it spinning around very nice, I will see if it adjusts backlash.

Wired the Mill today. I had read some people talked about them being loud. It is a bit louder than my BP but holy cow it just feels like this thing has tons of power, can't wait to mill something.

I pulled the Y axis ball screw out and removed the 200 BBs. The plastic shroud was binding against the ball screw. I had to turn it and take about .005 off of it to true it up on the outside, it is press fit into the ball nut. Took about .010 out of the inside as well, not sure why they have it on there. On one end of the ball nut there is a small felt ring that fits in a groove but on the plastic side there is nothing to prevent crap from getting into the ball nut. I am going to wrap a piece of felt around it with a clamp to keep it clean.
Turns very nice now.

Checked backlash and it is less than .0005

Tomorrow I am going to pull that spindle drive mess out.

 

[metron9]

Looking good so far. Question on this spring installation. Will a 3" hose clamp work for a spring clip? It looks like if I can slide 1/2 the width of the spring into the pocket on the press and then loosen the hose clamp while sliding the spring into the pocket it will work. How much boing is in this thing as it sits? If it uncoils is it hard to recoil it up? Safety goggles I imagine is a must.

This is how it was when I got it open (although I cleaned it up before the picture) That roll pin is pretty far back so if that nut comes loose a tad the whole thing will boing again. Should I use some lock tight on it before re assembly?

Not sure if I am going to replace this bearing, they want $750.00 for the exact replacement. It is a little stiff but I don't know if I have too much pressure on the outside nut. Should I be able to tighten it down and still have the bearings smooth as butter? It had lots of dirt and grime on it so I think it has micro pitting.

 

[metron9]

I finished replacing the quill spring, it was not connected. That went well and after removing the quill and cleaning the spline shaft I thought everything was going to be ok. I replaced the quill and adjusted the quill guard as the manual said to do. Moving the quill up and down I hear a scratchy sound and then something up higher is stopping the quill guard. Removed the quill again and this is what I found. I am happy now but going to eat supper before putting it back together.

 

[metron9]

New pictures. I finished the bulk of the work to attach a quill drive.

I used 3/4 Aluminum plate and a star 1 1/4" ball screw i found on Ebay.

The angular contact bearings I used are wheel bearings for a boat tailor top and bottom of the 3" aluminum housing.

I am using a 3/4 inch timing belt and 2 inch pulleys.

I used 3 longer bolts that hold the cover plate to mount an aluminum block to the side of the head with a 5/8 tapped hole to hold the center of the plate.

I won't be able to angle the head but i can still slide the head forward and backwards.

I will use a clamp with delren on the top and bottom to make the attachment from the aluminum to the quill. That will allow the little steel pin to slide a tiny bit horizontally so there wont be and binding due to misalignment. It's pretty close but not exact.

Now on to the computer, mach3 drivers and motors.

 

[metron9]

Finally it's up and running.
Need to add the Estop button, Limit and home switches.

excellorebuild.avi - YouTube

Ran the part through a few times. 120IPM motor max program was 60IPM I think
Back to zero no steps lost.

Testing X and Y the backlash is about .oo1 on the Y but better on the X. The X is stiffer to turn by hand and the Y I can push the table when the motor is not connected to spin the ball screw. I think for what I am doing with it it will be fine.

The gecko drivers use 10,000 steps per inch I did have to change the Z axes to 10210 , I guess the pulleys are not exact.