Bought a diamond in the rough mill probly

[justin1]

@John Conroy it's amazing how similar your mill looks to mine the pictures will be helpful thank you for them.


@jcdammeyer so far the VFDs are around 1300$ for name brand not as much select as 240v stuff or 375v though. One of the thoughts I did have was repowering head so I would be interested learning more about the servos. Is there any good right ups out there about doing that kind of conversion? I image custom adapter plate would need to be made but besides that probly could reuse pulleys system as long as shaft can be sized the same.

 

[jcdammeyer]

@jcdammeyer so far the VFDs are around 1300$ for name brand not as much select as 240v stuff or 375v though. One of the thoughts I did have was repowering head so I would be interested learning more about the servos. Is there any good right ups out there about doing that kind of conversion? I image custom adapter plate would need to be made but besides that probly could reuse pulleys system as long as shaft can be sized the same.

Check out my G3616 CNC conversion thread. There I show the adapter plates I made etc. I'm still amazed at how much smaller a 1.8kW motor is compared to the original 1.5kW. Mind you the torque on mine will likely be half of the original since it was max 1750 RPM and the AC servo is 3000 RPM. But I did set up for 2:1 to cut max RPM to 1500 and double the torque.

So far I've had more issues with slipping belts and not overloads. But then I don't do massive cuts either.

 

[justin1]

Got the mill knee unstuck toke about 5 hours, but there were a few things the old owner broke on there attempt at free up knee but all in all 90% fixable just have to replace the gib. rest is repairable. the only damage i created was some rolled threads from using drill to take table acme thread out and i melted a lube line... opps anyways here is some pictures from the ordeal. gonna try and get a hold of a king parts seller if i can find one and see what i can come up with for new gib.

 

[justin1]

some more pictures of stuff being taken apart. there was what looks like rust built up on top of weys any recommendations on how to remove doesnt seem some off with scraper was gonna maybe scotch brite it.

 

[justin1]

and last but not least the broken knee stand i was thinking of using some cast iron rod i have laying around to repair then re-drill holes in new locations. or other option i'm thinking of is just buying longer cap screws and fix the threads that are there and just not worry about it. as welding it could cause more issues then its worth.

 

[John Conroy]

What's wrong with the gib?

Could you post pics of the knee stand from different angles so we can see the damage better?

 

[justin1]

What's wrong with the gib?

some of it is missing at the bottom of it my knee is 18.5 wide with 1inch deep holes for the adjustment screws on each side, what is left of gib is 15 1/4 so im not sure how long the original gib is spose to be but currently its short not sure if i could just weld a thinner peace on the end so adjustment screws work again and call it good.

 

[140mower]

If buggered threads all all that's wrong, heli coil it and be done with it...... Welding would be my last choice.

 

[justin1]

If buggered threads all all that's wrong, heli coil it and be done with it...... Welding would be my last choice.

ye i'm kinda Leary with welding cast if it was a classic restoration I may try it but i think there is lots of meat left in casting so probly just gonna get longer bolts the threads i can see looks fine.

 

[Dabbler]

Is the slot still in the gibb for the adjuster? Usually a gibb is adjusted from one side, using a custom adjuster bolt - at least that is the way it has worked on the machines that have come through my shop...

 

[justin1]

Is the slot still in the gibb for the adjuster? Usually a gibb is adjusted from one side, using a custom adjuster bolt - at least that is the way it has worked on the machines that have come through my shop...

yes it is. it isnt like the bridgeport slot they just milled the corner of the top of gib off.

 

[Dabbler]

and last but not least the broken knee stand i was thinking of using some cast iron rod i have laying around to repair then re-drill holes in new locations. or other option i'm thinking of is just buying longer cap screws and fix the threads that are there and just not worry about it. as welding it could cause more issues then its worth.

If you have enough meat to tap deeper holes, and there is enough flat on the knee support, then going with longer screws seems like a good option. You can add to the bottom of the support with aluminum filled epoxy for greater support and draw file it flat.

yes it is. it isnt like the bridgeport slot they just milled the corner of the top of gib off.

Oh my. I'm imagining a pretty screwed up gibb and gibb support. I'm feeling bad that I am so far away. I wish I could help more.

 

[justin1]

If you have enough meat to tap deeper holes, and there is enough flat on the knee support, then going with longer screws seems like a good option. You can add to the bottom of the support with aluminum filled epoxy for greater support and draw file it flat.


Oh my. I'm imagining a pretty screwed up gibb and gibb support. I'm feeling bad that I am so far away. I wish I could help more.

i attached picture of the gib to my last post. I didn't even think about adding some jb weld to top on knee support i could do that as well but there is still lots of surface area so not sure if that will do much besides a visual thing. are there much loads on top of knee post or is it just the brass nut that takes most of the loads?

and all good advice is more then enough help, but ye would be nice to have some hands on help too but i think im doing good so far for my first time doing this lol. cant wait for the tuning of everything once its back together...

also what a stupid design lol why would you put a non sealed bearing were chips can fall in it no wonder why its was so crunchy when i was taking knee apart. should be easy enough to find replacement sealed bearing.

 

[jcdammeyer]

The Chinese new year is over and I'm just discussing the optimal replacement AC servo for the 550VAC 3 phase you have there. I sent him the photo of the motor cover plate.

I take it you have 220VAC 20A available? I'm asking for something that does 2000 RPM and just over 5HP. That's 16.226 ft-lb (22 NM)

 

[justin1]

The Chinese new year is over and I'm just discussing the optimal replacement AC servo for the 550VAC 3 phase you have there. I sent him the photo of the motor cover plate.

I take it you have 220VAC 20A available? I'm asking for something that does 2000 RPM and just over 5HP. That's 16.226 ft-lb (22 NM)

220v single phase yep 3 phase no, i'm not sure what the torque is on current motor is. I did notice grizzly sells a 3 hp motor for there mill G0797 thats 220v 3ph its about 300$ usd. looks like it would be bolt on more or less. im currently considering building a pony RPC from a 7.5-10hp motor thats 575v then running step up transformer on the single phase side. was gonna check local scrap yard see if they had anything laying around.

i did look at your conversion look sweet, not sure if my shop is set up enough to do it properly currently. but im still curious on what is comparable servo wise

MOTOR 3HP 220V/440V 3-PH V3.08.18 - Grizzly Industrial

Grizzly P0797308V3 - MOTOR 3HP 220V/440V 3-PH V3.08.18

www.grizzly.com

 

[jcdammeyer]

220v single phase yep 3 phase no, i'm not sure what the torque is on current motor is. I did notice grizzly sells a 3 hp motor for there mill G0797 thats 220v 3ph its about 300$ usd. looks like it would be bolt on more or less. im currently considering building a pony RPC from a 7.5-10hp motor thats 575v then running step up transformer on the single phase side. was gonna check local scrap yard see if they had anything laying around.

i did look at your conversion look sweet, not sure if my shop is set up enough to do it properly currently. but im still curious on what is comparable servo wise

MOTOR 3HP 220V/440V 3-PH V3.08.18 - Grizzly Industrial

Grizzly P0797308V3 - MOTOR 3HP 220V/440V 3-PH V3.08.18

www.grizzly.com

So Donald got back to me. I don't think you'll like the price but then it's also almost 6HP where likely 3HP for home shop is probably fine.

"Servo motor 180SM-M2220NAL and servo drive SDD50NK10D with 3 meters cable charges 740USD. Fedex charges 220USD to Canada"

If you want only 3HP I'll ask. The FedEx cost won't change much. I've had to pay that for the motors I ordered. What I found is when there are a few motors in the order that the cost was less than through EBAY for alternate and perhaps lower quality motors.

I'm running a 1.8kW motor on my mill. My V Belts slip so I can't say if I've ever stressed the motor to the point where it creates a following error under load.

 

[justin1]

ouch and would still have to pay import taxes on that as well but pretty much any option i look at besides building an pony style RPC is around 1000$ to 3000$. only reason the pony style RPC would be cheaper is i have half the stuff to build it and rest can be scavenged its just takes time to get the right parts. the 575v diffantly throws a level of complexity too the mix.

for the belt slippage try some belt dressing or upgrade belt to a higher quality new belt even good belts start to lose traction with age. but for the high torque stuff timing style belts go a long way but may not be do able without reworking your whole setup

 

[jcdammeyer]

My plan is to use toothed belts and pulleys. But first I want my power draw bar working and maybe even the ball screws. Way too much play in the X axis.

From a money perspective, when I did the math, the 3 phase motor, a good quality VFD and the 0-10V to drive if from the PC for CNC control were more expensive than the AC servo which can also do very slow speeds if I want. And I'd still need an encoder to deal with power tapping and just speed regulation. For me the math worked out that even with shipping (and a couple of other motors) the cost of the AC Servo was less than 3 phase + VFD plus US shipping, duty etc. But for a bigger motor it may be difference.

The reason I want to go toothed belts is then I can use the encoder on the motor with the appropriate ratio if it's not 1:1 for tapping and speed feedback. At the moment now the two pulleys I made aren't quite the same diameter so the speed of the motor doesn't quite match the spindle.

 

[jcdammeyer]

You can see why Bergerda suddenly seemed like such a bargain for me considering I was also converting the knee from stepper motor to AC servo. And then X and Y changed from problematic DC Servos to AC servos.
This is what Donald Chen at Bergerda just emailed me.
"130SM-M1025NAL with servo drive whole set quote 400USD"
Plus the shipping of course.
I've attached the motor spec sheet.

Other than shipping and of course the labour to mount a different size motor, the Grizzly Motor at $300 US plus shipping (Heavy) and a VFD for anything from $150 to $500 plus shipping again.

 

[6.5 Fan]

Good that the damage was not extensive. I would second Dabbler's suggestion for repairing the knee post, epoxy and file flat. the a longer bolt.