Chevalier 2040 CNC Bed Mill Restoration

[coolidge]

You're going Centroid, right? That ought to be pretty straightforward, it's not vastly different from the PMDX hardware I collected a few years back (and hope to return to eventually). Other than maybe or maybe not the servos, is there anything else you're going to salvage from the old system?

I believe so, it seems to be the better yet reasonable cost choice guys are using on CNC conversions. But I have not gotten to researching this beyond a half hour quick pass.

I converted one of the early IH mills to CNC years ago so this won't be my first rodeo. Still a lot has changed. I would not mind getting another 1k rpm out of this but don't know if the spindle or bearings can handle it.

 

[IHinIN]

2. The variable speed belt drive needs work for sure. I'd say a rebuild or conversion to VFD speed control.

Check the moving half of the motor pulley. My mill had a noisy head when I got it. The plastic bushings in the pulley and the key were shot. I epoxied in new bushings and made a new bronze key. Nice and quiet now.

 

[coolidge]

Check the moving half of the motor pulley. My mill had a noisy head when I got it. The plastic bushings in the pulley and the key were shot. I epoxied in new bushings and made a new bronze key. Nice and quiet now.

I saw those in rebuild youtube video last night of this type of VS belt drive.

To me my spindle feels like there's slop or backlash in the gears. I didn't pay attention to whether it was the high or low gear that was the worst but its present in both. There's a metallic clink at the end of the free play. Maybe 1/4 inch of free rotation then you can feel the belt and motor. So something is amiss. I see the variable pulley is pretty rusted up there also.

 

[pontiac428]

You might see a tiny bit of backlash from the bull gear in low range. It could also be in the keys. I wouldn't read too much into it at this point, it might go away when you lube the upper head. Push a little spindle oil in the top fitting to clear any dried grease then pump in some fresh red grease when you have it under power. Other than getting things clean, the odds are in your favor that the head is good.

 

[coolidge]

You might see a tiny bit of backlash from the bull gear in low range. It could also be in the keys. I wouldn't read too much into it at this point, it might go away when you lube the upper head. Push a little spindle oil in the top fitting to clear any dried grease then pump in some fresh red grease when you have it under power. Other than getting things clean, the odds are in your favor that the head is good.

On that subject, I was using red grease but found the oil separated out over time. For a while I have been using blue marine grease which seems indestructible.

If the head is good that would fantastic. I can live with this style variable speed for now. Evaporust will eliminate the rust up top. I'm guessing from non-use and there's no grease or oil on those.

One other point in favor of electronic speed control though, the ability to program spindle speed into the gcode programs. Plus I saw a need little video last night with a CNC tip of reversing the spindle to shake off plastic shavings from the tool.

 

[pontiac428]

Marine grease spooks me because it's so hard to clean off or flush out. It's also a low speed grease for trailer wheel bearings, so limited applications. I'm pretty sure the top end zerk feeds the low range gear hubs and mechanism as well as the gear teeth. It's a pretty generic NGLI-2 spec on the lube schedule (typical for BP clones, at least, so take that with a grain of salt) but it's worth using a premium grease over whatever is handy, especially if it doesn't meet spec.

Can you get more RPM out of the spindle? Possibly, but you're working with a 3 HP head and the power applied will fall off as spindle RPM goes up. If you're not struggling to meet production demands that require pushing feeds to the point where you are RPM limited, then it may not make sense to do it just to see if you can. Production CNC machines have much more power at the spindle than a BP head does. Like double digit kilowatts. I think what you've got started will have a very comfortable work envelope as-is.

 

[coolidge]

Marine grease spooks me because it's so hard to clean off or flush out. It's also a low speed grease for trailer wheel bearings, so limited applications. I'm pretty sure the top end zerk feeds the low range gear hubs and mechanism as well as the gear teeth. It's a pretty generic NGLI-2 spec on the lube schedule (typical for BP clones, at least, so take that with a grain of salt) but it's worth using a premium grease over whatever is handy, especially if it doesn't meet spec.

Can you get more RPM out of the spindle? Possibly, but you're working with a 3 HP head and the power applied will fall off as spindle RPM goes up. If you're not struggling to meet production demands that require pushing feeds to the point where you are RPM limited, then it may not make sense to do it just to see if you can. Production CNC machines have much more power at the spindle than a BP head does. Like double digit kilowatts. I think what you've got started will have a very comfortable work envelope as-is.

100%, for sure my tractor grease will get nowhere near it. Well actually I'm using the blue marine on the tractor LOL. I don't cheap out when it comes to lubrication or wait the BS 10k miles before oil changes on trucks that cost more than my first house.

It's a factory 5hp 3ph motor by the way. Oh yeah, 5hp baby. It's possible I'm getting overly excited about this project.

I was hoping to get 5,000 rpm that's what the PM940V offers. But it's not a deal killer. 4k is already spinning pretty fast. That's what the original Haas mini mills and toolroom mills had. More than 5k is really wasted unless the machine can move on it's access faster for high speed machining or something.

After watching that video last night I was thinking about removing the head to work on it. Then I went into the garage and looked at it, christ just the head not what it's attached to is WAY large. Bigger than my old PM knee mill head for sure. I have a couple of 2 ton shop crane but man I'm wishing I hadn't sold the gantry crane now.

 

[pontiac428]

Was it this video by chance? These guys tear BP heads down like wham, bam, thank'ya ma'am.

 

[coolidge]

Was it this video by chance? These guys tear BP heads down like wham, bam, thank'ya ma'am.

That's exactly the video I watched last night and saved for future reference. I noted more than a few gotchas, tips and tricks that guy shared.

He was going at it like a madman. I was like bro, you are going to break something.

 

[mksj]

If you are planning on CNC, most likely you will not be hogging out large chunks of metal a low speeds, more lloking at higher spindle RPM and feed rates. Some of the mill retrofits go to a VFD and a inverter/vector type motor to cover a wider speed range and use a direct pulley drive.. I am not sure of the value of a Reeves drive with continuous running that often occurs with CNC. Might have been what they had at the time, but there may be better drive options these days. Most of the smaller knee mill digital heads are direct belt drive and a back gear, my knee mill with a 3 Hp motor covers 40-450 RPM in back gear and 400-4500 RPM in direct drive. The motor runs from around 20-200 Hz. In previous conversions with RF45 type mills, quite a few individuals doing CNC conversions stuck a 3 Marathon BlackMax on the head and ran the motors to 6,000 RPM. I have also done quite a few lathe installs with their 5-10 Hp versions. BLDC with an encoder might also be a consideration for power tapping and positional control. Jim Dawson has a lot of experience in this area as well as the control conversion to more modern architecture, might be worthwhile reaching out to him. There have been a few others that have done similar modernization of older CNC mills.

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A rattling noise or play in the spindle could be a worn Reeves drive, could also be the crown gears in direct drive. Parts for some of the Reeves drives can be quite expensive if even available, a direct drive belt system might be a more cost effective option if parts are not available/repairable.