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Questions about a power feed on my 833T

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7milesup

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as it states I have a as it states I have a Precision Matthews 833 T milling machine. I would like to put a power cross feed on the x axis and don't want to spend a lot because I'm probably going to convert it to a CNC at some point down the road here. So If spent a lot on a power feed I would just be throwing good money after bad.
Precision Matthews sells a power feed specifically for the 833T. It is frankly more than I wanted to spend on an elcheapo feed. PM points out though that is specifically for that mill. The reason, I believe, is that the lead screw is 15mm but then there is an adapter that bumps it up to the standard 5/8" shaft. It ends up sticking out a long way.
So why could I not modify a standard power drive with an aluminum standoff so that I can utilize the 5/8 shaft? I have a ton of 3/4" 5083 tooling plate here with obviously high tolerance. Is there something that I am missing? I mean, we are machinists, I expect to have to rework stuff. ;)

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Cadillac

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You said it your a machinist modify it. What’s a standard power feed go for compared to a pm one? I don’t exactly know what your talking of. If your talking of making a mounting plate to mount a powerfeed that shouldn’t be to hard. Have at it. Or open up pulley or drive that connects to the 15mm or 5/8 you need?
 
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mksj

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How about putting a stepper motor on it and just powering it directly or getting a wiper motor with a DC supply. Otherwise a power drive is going to run you between ~$250-325, so not much cost difference in getting a cheaper one that may or may not work. If just short term, search for a DC gear motor and cobble something together, whether direct drive with a coupler that you can bore to the shaft dimensions or a belt drive that you can convert to CNC at a later point. There are also other types of AC servo drives from DMM or DC servo drives that can be adapted. You will most likely swap out to ball screws so the shaft connections will most likely change. I adapted a AC gear motor direct drive with a VFD on my last mill, but cost wise I do not think you would be saving much going that route.

http://www.dmm-tech.com/index.html
https://www.teknic.com/products/clearpath-brushless-dc-servo-motors/
http://www.motioncontrolproducts.com/
 
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Tekwip

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Go for it. With a lathe and milling machine you can make any part needed. One thought though, you can buy the Precision Mathews power feed made for the 833t and resell it at a reduced price to another 833t owner when you go CNC.
 

7milesup

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How about putting a stepper motor on it and just powering it directly or getting a wiper motor with a DC supply. Otherwise a power drive is going to run you between ~$250-325, so not much cost difference in getting a cheaper one that may or may not work. If just short term, search for a DC gear motor and cobble something together, whether direct drive with a coupler that you can bore to the shaft dimensions or a belt drive that you can convert to CNC at a later point. There are also other types of AC servo drives from DMM or DC servo drives that can be adapted. You will most likely swap out to ball screws so the shaft connections will most likely change. I adapted a AC gear motor direct drive with a VFD on my last mill, but cost wise I do not think you would be saving much going that route.

http://www.dmm-tech.com/index.html
https://www.teknic.com/products/clearpath-brushless-dc-servo-motors/
http://www.motioncontrolproducts.com/
Hi Mark. Never thought about a wiper motor or such and "cobbling" something together. I did plan on converting all of the screws to ball screws at some point. That is what started my whole "get something cheap going" initially, which usually never works for me and I end up kicking myself later on. I do enjoy the challenge of making "alternative" options work though. I am somewhat familiar with your lathe thread; do you have a thread on how you did your mill?
I have all of those websites you posted bookmarked already :) Quick question... how do you control the servo drive without the full blown software to run it. I am assuming that it would be some sort of PWM controller?

Go for it. With a lathe and milling machine you can make any part needed. One thought though, you can buy the Precision Mathews power feed made for the 833t and resell it at a reduced price to another 833t owner when you go CNC.
I was thinking that 833T owners are about as rare as hens teeth, but maybe I am wrong. That might be a viable option though.
 

mksj

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Depends on the drive system you use, I would contact DMM, etc. to see what they suggest. DC steppers there are some circuits out there for manually driving them, but you run into issues with damage from the stepper if you manually turn the crank. You would need some form of disconnect (at least what I have read). AC drives it is not an issue, one reason why I went with an AC gear motor and VFD for the X and Z drive on my last mill. Lots of people just use something like a DC wiper motor with a variable DC power source. You can build up everything for CNC drive and just use an adapter mounting plate in the interim.

These are Bodine AC inverter gear drives, both are directly connected via flex couplers. The X drive was good for up to 30 IPM. AC drives like these do not do well at low speed like below 5 IPM or below say 10-15 Hz. This ran to 110Hz. At the end of the day it would have been better to get a manufactured drive, but they did not make any for this particular mill. They are commonly converted to CNC.
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Another variation
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7milesup

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Awesome Mark. That is some good info. I should have posted in my first reply that I was planning on servo motors if I converted to CNC. Do you have a build thread on that one?
 

mksj

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Sorry no build thread, it was about 8 years ago. Pretty basic, used aluminum 1/2" stock for the mounts, the motors were direct coupled to a flex couplers that I bored/threaded as needed to connect to the leadscrew. If I recall the couplers were split to lock onto the leadscrew shafts. Nothing special other than laying it all out and aligning everything. The was some vertical adjustment to line up the motor shaft and the flex couplers also allow some misalignment. Alternative would be a cogged belt drive which would be more compact. Servo drives are preferred over stepper, so that is a good choice. Haven't worked with CNC, so can't offer any specifics.

Inexpensive single axis stepper controller https://www.automationtechnologiesinc.com/products-page/cnc-controller-box/1-axis-cnc-servo-stepper-motor-motion-programmable-controller/
You may build out the components for a CNC servo system and just set it up with 1 axis drive for now and use a pendent drive or something similar to set the Mach 3 jog speed J+/J- and manual direction buttons. Then build it out to a full CNC system at a later point.
https://www.ebay.com/itm/4-Axis-USB-Pendant-Handle-Wheel-Engraving-Numerical-Remote-Control-For-Mach3-CNC/132763026325
 
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