Well, I finally sold my round column Harbor Freight mill (link) last week so it is finally time to get my G0704 up and running on CNC. I had measured, designed and made all of the parts for the G0704 on the round column mill, but had to wait until it sold so that i could but the steppers, drivers, and BOB. I got all but the BOB and now have the mill mostly assembled. It has gone together and been taken apart probably about a dozen times over the past few months, but hopefully this is the last time before it makes some chips of its own. I already have some parts I need to make for my other numerous hobbies.
The summary of the conversion and the components, along with some future plans is as follows:
- Automation Technologies (Keling) 570 oz-in steppers on X, Y and Z
- Automation Technologies (Keling) 6050 drivers
- 48V 13.5A Dell server power supply
- Chinese manufactured parallel port BOB
- Salvaged 2.6 GHz pentium 4 PC
- USB Game controller for a pseudo pendant
- LinuxCNC (I am going to give Mach3 a try this time around though)
- Thompson rolled ballscrews with double nuts on all axes
- Angular contact bearings on all ballscrews
- Machined aluminum end plates on all axes
- Lapped ways on all axes
- Way lube system started (ready to plumb)
- Home/limit switches planned using proximity switches
- 4th axis planned (already have a 6" rotary table)
- Possibly a different spindle motor and belt drive
As for the machine tour, I'll start at the end and then go through the conversion.
Below is a picture of how it sits in the barn right now. Well almost. In this picture I had forgot to put the Z-axis way cover on which has since been corrcted.
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Below is a pic of the Z-axis ballscrew setup. I found that the Thompson ballscrews are too hard for the lathe tooling I have to be able to cut threads,so I welded on a chunk of 5/8" diameter steel rod on the end of each ballscrew and then proceeded to machine that. The threaded end just has a 12mm straight section followed by a 12mm fine pitch thread on it, That's all. You'll see why later. In this picture you can see that the double ball nut arrangement has been installed.
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Here is a closer view of the double ball nut. Starting from left to right in the picture. First is the "fixed" ballnut that is threaded into the aluminum slide mount the attaches the Z-axis slide. This part is in 2 pieces with a tight fitting key. This was done that way so that it would be fit through the top of the column while assembled on the screw. The second ball nut is next. Its threaded end is simply protruding into a 1" diameter bore in the end opposite of the slide mount. on the right end is an aluminum plate that has a stack of wave washers between the plate and the ball nut This plat is attached to the slode mount with a pair of 1/4" diameter bolts to provide preload to the ball nuts to eliminate backlash. The preload on all axes is about 120 pounds.
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Here is the column top cap with stepper standoffs and the end of the ball screw. On each of the ball screws, I have a wave washer in the assembly sack to provide preload to the angular contact bearings without having to monkey around with double nuts.
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Here is how my motor couplers are made. These are home brew Olham couplers made from aluminum with a HDPE puck. The motor side just has a 3/8" reamed bore with a 1/4"-20 set screw to lock it on the shaft. The ball screw side has a 12mm threaded bore and after threading, I split the coupling. I have two 1/4"-20 SHCS that clamp the coupler onto the threaded end of the ball screw like a split collar. With the threads, I can put the SHCS's in just snug and thread the coupling half onto the ballscrew. I then tighten it up to compress the wave washer for preload and then lock the SHCS's. Seems to work great. We will see how it works in operation soon.
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Here is the y-axis ball screw setup. Same principal as on the z-axis, just different geometry. Also, I cut the threaded end off of the floating ball nut to reduce the length of the assembly.
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And the Y-axis motor mount/thrust block. Same angular contact bearings, but here, I have a little aluminum puck with a recess that acts as a pseudo labyrinth type seal to keep crap out of the bearings. The angular contact bearing on that side protrudes from the mounting block a bit to accommodate the seal/puck. You can see on this one that the wave washer is between the puck and the coupler.
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Carriage installed, Y-axis hooked up, and X-axis screw in place.
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At this point the table is installed and the end plate at the floating end of the ballscrew is installed. On the floating end of the x screw, I did machine a 12mm diameter into the ball screw to fit the bearing.
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And the opposite end awaiting the coupler and motor.
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Here are a couple pics of the Y and Z axis with motors and couplers installed. Somehow I didn't get a picture of the X axis at this point.
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Well that is about all for now. I think this setup is going to work pretty well. Each axis moves very smoothly after lapping. Next is to wire up the electronics. I already have the PC set up for dual booting LinuxCNC and Windows XP Pro with Mach3 and LinuxCNC installed. I am still waiting for the BOB to arrive but will have the power supply and drivers temporarily wired for testing tomorrow. As soon as the BOB gets here I can start moving under CNC control.
I will post my plans of the parts for this conversion when I get it tested and have a chance to clean up the drawings a little.
Once the mill is up and running I plan to convert my little 9x20 lathe to CNC.
Enjoy,
John B.
The summary of the conversion and the components, along with some future plans is as follows:
- Automation Technologies (Keling) 570 oz-in steppers on X, Y and Z
- Automation Technologies (Keling) 6050 drivers
- 48V 13.5A Dell server power supply
- Chinese manufactured parallel port BOB
- Salvaged 2.6 GHz pentium 4 PC
- USB Game controller for a pseudo pendant
- LinuxCNC (I am going to give Mach3 a try this time around though)
- Thompson rolled ballscrews with double nuts on all axes
- Angular contact bearings on all ballscrews
- Machined aluminum end plates on all axes
- Lapped ways on all axes
- Way lube system started (ready to plumb)
- Home/limit switches planned using proximity switches
- 4th axis planned (already have a 6" rotary table)
- Possibly a different spindle motor and belt drive
As for the machine tour, I'll start at the end and then go through the conversion.
Below is a picture of how it sits in the barn right now. Well almost. In this picture I had forgot to put the Z-axis way cover on which has since been corrcted.
Below is a pic of the Z-axis ballscrew setup. I found that the Thompson ballscrews are too hard for the lathe tooling I have to be able to cut threads,so I welded on a chunk of 5/8" diameter steel rod on the end of each ballscrew and then proceeded to machine that. The threaded end just has a 12mm straight section followed by a 12mm fine pitch thread on it, That's all. You'll see why later. In this picture you can see that the double ball nut arrangement has been installed.
Here is a closer view of the double ball nut. Starting from left to right in the picture. First is the "fixed" ballnut that is threaded into the aluminum slide mount the attaches the Z-axis slide. This part is in 2 pieces with a tight fitting key. This was done that way so that it would be fit through the top of the column while assembled on the screw. The second ball nut is next. Its threaded end is simply protruding into a 1" diameter bore in the end opposite of the slide mount. on the right end is an aluminum plate that has a stack of wave washers between the plate and the ball nut This plat is attached to the slode mount with a pair of 1/4" diameter bolts to provide preload to the ball nuts to eliminate backlash. The preload on all axes is about 120 pounds.
Here is the column top cap with stepper standoffs and the end of the ball screw. On each of the ball screws, I have a wave washer in the assembly sack to provide preload to the angular contact bearings without having to monkey around with double nuts.
Here is how my motor couplers are made. These are home brew Olham couplers made from aluminum with a HDPE puck. The motor side just has a 3/8" reamed bore with a 1/4"-20 set screw to lock it on the shaft. The ball screw side has a 12mm threaded bore and after threading, I split the coupling. I have two 1/4"-20 SHCS that clamp the coupler onto the threaded end of the ball screw like a split collar. With the threads, I can put the SHCS's in just snug and thread the coupling half onto the ballscrew. I then tighten it up to compress the wave washer for preload and then lock the SHCS's. Seems to work great. We will see how it works in operation soon.
Here is the y-axis ball screw setup. Same principal as on the z-axis, just different geometry. Also, I cut the threaded end off of the floating ball nut to reduce the length of the assembly.
And the Y-axis motor mount/thrust block. Same angular contact bearings, but here, I have a little aluminum puck with a recess that acts as a pseudo labyrinth type seal to keep crap out of the bearings. The angular contact bearing on that side protrudes from the mounting block a bit to accommodate the seal/puck. You can see on this one that the wave washer is between the puck and the coupler.
Carriage installed, Y-axis hooked up, and X-axis screw in place.
At this point the table is installed and the end plate at the floating end of the ballscrew is installed. On the floating end of the x screw, I did machine a 12mm diameter into the ball screw to fit the bearing.
And the opposite end awaiting the coupler and motor.
Here are a couple pics of the Y and Z axis with motors and couplers installed. Somehow I didn't get a picture of the X axis at this point.
Well that is about all for now. I think this setup is going to work pretty well. Each axis moves very smoothly after lapping. Next is to wire up the electronics. I already have the PC set up for dual booting LinuxCNC and Windows XP Pro with Mach3 and LinuxCNC installed. I am still waiting for the BOB to arrive but will have the power supply and drivers temporarily wired for testing tomorrow. As soon as the BOB gets here I can start moving under CNC control.
I will post my plans of the parts for this conversion when I get it tested and have a chance to clean up the drawings a little.
Once the mill is up and running I plan to convert my little 9x20 lathe to CNC.
Enjoy,
John B.