MANUAL 13x40 lathe to CNC conversion with vfd

sortafast

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Update:
I got home early today and got to do a little work on the z axis. I managed to mess up the first round measuring wrong but I think I have all the main dimensions right. The servos should be here next week so I am trying to push this weekend to get the ballscrews and servo mounts finished.

Quick video making the z axis servo motor mount at 7000 rpm with my cnc converted Precision Mathews PM45m mill. I was paranoid and slowed it down to 30 ipm. The mill does fine at 70...


at 7k with a good, aluminum specific endmill you should be able to do way more than 30IPM. I run a Maritool carbide Al specific rougher at 3200 (max rpm for my machine :( ) at 40ipm at a 0.200" DOC with the vise barely holding on to the stock and I think I could go higher if I had a better grip. The key is a good enclose, good coolant and a good tool. Its amazing what one can do with that stuff.
 

gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Yeah you are right- the mill is able to do 75 ipm but cutting a piece for the first time, I go super slow. I spent 10 minutes in cad and 5 minutes with my meshcam cam software and went straight to cutting the part. Mostly it works but once in a while :p
 

sortafast

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Yeah you are right- the mill is able to do 75 ipm but cutting a piece for the first time, I go super slow. I spent 10 minutes in cad and 5 minutes with my meshcam cam software and went straight to cutting the part. Mostly it works but once in a while :p
I usually run stuff slow at first too. Gives time to see if one messed anything up in the planning/programming stages. Also allows you to see if you have everything clamped down good and tight. Nothing worse than shooting a part out of the vise and toasting a $50 endmill or $80 worth of inserts. I got a drawer full of reminders of that.
 

gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Update:

I made some real progress and got the z axis largely done. I made a monolithic ballnut block that is 1.8" thick and mounts to the saddle. I also made the two bearing blocks that support each end of the ballscrew. The trick was getting everything square and aligned. I was rewarded by a z axis that moves very smooth without any binding on the full range. The ballnut block has a "L" shaped cutout for my skarf guard I am making to protect the ballscrew. I have to finish the other 2 sides of the "box" I am building under the saddle that will protect and house the x axis servo and pulleys still but I can't wait to get this thing running. It is so stiff and solid compared with the way the lathe was stock and there is absolutely no perceptible backlash.

Pics:

zaxis1.jpg




zaxis3.jpg



I will have to trim this a tad to compensate for the saddle clamp that goes on the underside of the saddle:
zaxis4.jpg
 
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sortafast

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Do you think there will be any issues with flex under heavy loads because of the L shaped cut out? I doubt it, but it could be a possibility.
 

gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Do you think there will be any issues with flex under heavy loads because of the L shaped cut out? I doubt it, but it could be a possibility.

The block is a scrap of 7075 t6 aluminum I had left and measures 1.8" thick. It is bolted to the hard steel ballnut which has a 3/8" thick flange.

FYI, 7075 t6 alloy has a tensile strength more than 1018 steel:

1018 = Tensile Strength, Yield 380 MPa 55100 psi
6061 t651 = Tensile Strength, 324 MPa, 47000 psi
7075 t651 = Tensile Strength, 572 MPa, 83000 psi

The steel saddle should deform before the ballnut block mount. The ballnut block will have additional sections to form a box to shelter the x axis servo, pulleys and further support the block. Based upon how it moved using a drill and putting leverage on it, other parts of the lathe will break first without even supporting it further.
 
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gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Update:

I re-thought my x axis aluminum platform and converted to a massive 8"x 8" x1.5" steel block that sits on one side of where the aluminum block went. The steel is much heavier at 28 lbs but the main reason was to preserve the max stock capacity of the lathe.

The 13x40 lathe can handle stock 8" in diameter with the right chuck but with the aluminum going the whole width of the cast iron x axis base, I inadvertently cut that in half. I don't normally turn giant stock but definitely want to be able to in the future. Here is my 4" extension on the PM45m mill that is 8" diameter and brings my PM45M mill to 11.5" y travel:



head%20extension2.jpg



With the new x axis design, the steel block sits on one side and should be able to handle a couple of tool holders or a turret but allows large stock to still be turned. It is also much more rigid. Making this change meant drilling 8 holes through the 1 1/2" steel block and machining a step and pad out for the x axis ball nut mount and making a new ball nut mount also. I also upgraded the mounting bolts for the block to 5/16" for holding the steel block to the x axis base. Took the whole weekend and then the wife chased me in last night before I could snap pics. I will post some when I get home but it is a significant upgrade. I also got word the DMM Tech servos and drives should be here on Weds so it should be a good week.

Mark
 
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gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Here are the shots for the new steel x axis. There is a noticeable difference in the stiffness. I will add some bellows like these to cover the ballscrew:

http://www.arceurotrade.co.uk/Catalogue/Machine-Spares/Machine-Bellows


Re-doing the axis wasted a nice giant piece of mic6 but I regained my full stock capacity.

steel1.jpg


steel2.jpg


steel3.jpg


I think I will have enough space for 2 QCTP and a boring fixture in the middle. That way I can run both left and right side tools.

I can't wait for the servos to get here already...
 

gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Update:

I was able to make some real progress and the CNC conversion is almost done mechanically. I still need to add the the limit/homing switches and run the one shot oiling system, enclosure etc(It's never really done!)

I tried to document the the build with a lot of pics so you can see was involved. The electronics are easy with the DMM servos and it is almost plug and play.

Enough yapping, here are the pics:

z servo mounting block

z-blocks.jpg


new "saddle". This holds the servo and ball nut in place and allows for a scarf guard:

new-saddle.jpg


zblocks2.jpg


saddle2.jpg


x axis servo plate with boss cut for the mount:

xservoplate.jpg


New DMM Tech servos:

dmmservos.jpg


drives:

dmmtechdrives.jpg


back-oofservoplate.jpg



saddle3.jpg



mountedxservo.jpg


saddle4.jpg


zservomounted.jpg


zservomounted2.jpg




and finally, an overall shot:

finished1.jpg



Thanks for looking...
 
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MRsDNF

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

It look amazing. Thanks for all the pictures and all the best for the finish.
 

sortafast

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Looking good. Are you running aluminum specific endmills to cut the aluminum? Also, for countersinking screw holes, I love running 82° mill drills in my cnc. Comes out clean looking every time.
 

gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Looking good. Are you running aluminum specific endmills to cut the aluminum? Also, for countersinking screw holes, I love running 82° mill drills in my cnc. Comes out clean looking every time.

I used a 3/8" carbide 2 flute end mill for most of the work. The countersink was from the local hardware store and designed for wood and soft materials and I had a lot of chatter. I need a proper angled endmill like you are talking about for chamfering and countersinking. All the countersinks are permanently hidden at least :p
 

sortafast

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

you need to get you some 3 flute aluminum specific endmills. Once you get them you will wonder how you ever got along with out them. ;)
 

precisionworks

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

The first rule on countersinks is slow down when they chatter - the second rule is slow down even more if the chatter doesn't stop. I normally c-sink between 25-100 rpm when using a larger tool to chamfer a flashlight body.
 

gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Heh, I didn't look up speeds and feeds on countersinks. 2k rpm sounded good... until the chatter started
 

sortafast

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Heh, I didn't look up speeds and feeds on countersinks. 2k rpm sounded good... until the chatter started
run a mill/drill on a spiral/helical tool path down to depth and it its money every time. Takes a little bit of work to figure out how far down and over you have to go, but once dialed, you are GTG and your countersinks will always look awesome. Just need an 82° for SAE bolts and a 90° for Metric, and a few different diameters to accommodate a wide variety of bolt sizes. Do it and don't look back. I think I picked up some Garr carbide mill drills for like $16ea at the local machine tool supplier. They can be had cheaper online, maybe. Well worth the expense though. I use mine for quick deburring of tricky parts, beveling edges for looks and function, countersinking holes and occasionally for milling ends of things. I love them.
 

gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

Update:

Been super busy at work and waiting on some parts, but I finally got things moving!

I remade the z axis to use a timing belt and pulleys like the x axis.

FYI, you don't need to be a programmer to use this because most lathe operations are covered by wizards in Mach3 turn including inside and outside threading, turning tapers, etc. Worth looking at:

http://www.micro-machine-shop.com/Mach3Turn_1.84.pdf

Here is a a video of test gcode created by using the wizard to cut a rounded "filet". This would be almost impossible to cut manually. Fill in a few perimeters and click cycle start:




https://vimeo.com/104368587
 
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gt40

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Re: MANUAL 13x40 Jet lathe CNC conversion with vfd

FYI, I wanted to take a moment to share the outstanding tech support I have been getting over with servo company I used to do the conversion, DMM Tech. I fried a breakout board by dumping high voltage into it(my fault) and they overnighted a replacement free of charge and free shipping from Canada. They also spent over an hour on the phone while we traced down a random interference issue. You want to keep the servo power cables away from the control ones. I had them touching and the current fields messed with the control. They just walked me through it while we tested some stuff over the phone and everything is just working.

They are also helping me set up a hall sensor to pick up the spindle rpm as I hope to be able to set up constant surface speed as well as for threading. There are boards for sale but the tech walked me through using a cheap hall sensor I had laying around to save money.
 
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