Restoring BP ways and spindle bearings? - Cost and Effort?

bigwave · Mar 2, 2021

Hi folks,

I'm going to look at a BP J-head Series 1, 1.5HP, round-dial variable-speed unit tomorrow. The previous owner says the gibs are tight around the center to adjust out the play and therefore, it's tight at the extremes of travel(clapped out?).

How much effort is it to restore the ways/gibs?
I'm game for hand scraping but my goal isn't machine restoration..:-)

Also, the owner reports a bit of vibration at high-speed (4K RPM). I have the same question for the spindle bearings & quill - I'll measure the run-out tomorrow but I'm wondering what the effort/cost is to replace those.

Thanks ahead of time,
Dave

Rprecision · Mar 2, 2021

To me the spindle bearings are not outside the realm of DIY service and or minimal cost service.

Grinding and scraping the ways is not. Part is the cost of transportation to and from a reputable company. It certainly can be done, frankly its on my bucket list of learning, but not cost effective.

bigwave · Mar 2, 2021

Rprecision said:
To me the spindle bearings are not outside the realm of DIY service and or minimal cost service.

Grinding and scraping the ways is not. Part is the cost of transportation to and from a reputable company. It certainly can be done, frankly its on my bucket list of learning, but not cost effective.

Thanks for the reply. In reading a bit more in this forum and others, it seems a steep hill to climb and not worth considering restoring the ways (professionally, at least). This is for a home shop so it might be ok for now.

-D

Homebrewblob · Mar 3, 2021

bigwave said:
Thanks for the reply. In reading a bit more in this forum and others, it seems a steep hill to climb and not worth considering restoring the ways (professionally, at least). This is for a home shop so it might be ok for now.

-D

The word restore is a funny thing.

It’s virtually impossible to restore a machine tool such as a mill to original specs period.

Rebuilding a machine tool is more appropriate, you can rebuild a machine tool to original specs or even better depending on technology available and money/skill.

A diy garage rebuild and a professional rebuild have no difference, only tolerance.

Technically you don’t have to grind or plane the ways, you could just do it the ole hard way and hand scrap them down and then flat/parallel.

To scrap the ways yourself to a lesser tolerance then “rebuilt” specs would still require a very significant set of skills, tools and experience.

You can think of rebuilding machines as a spectrum. Rust oleum being on the low end of said spectrum.

Ways and spindle bearings?
You may even need the quill itself trued up.

If you got the machine for free and had to do all this work it may still end up more expensive with worse tolerances then a used bp on the market.

It’s definitely the more time consuming route.

bigwave · Mar 3, 2021

Homebrewblob said:
The word restore is a funny thing.

It’s virtually impossible to restore a machine tool such as a mill to original specs period.

Rebuilding a machine tool is more appropriate, you can rebuild a machine tool to original specs or even better depending on technology available and money/skill.

A diy garage rebuild and a professional rebuild have no difference, only tolerance.

Technically you don’t have to grind or plane the ways, you could just do it the ole hard way and hand scrap them down and then flat/parallel.

To scrap the ways yourself to a lesser tolerance then “rebuilt” specs would still require a very significant set of skills, tools and experience.

You can think of rebuilding machines as a spectrum. Rust oleum being on the low end of said spectrum.

Ways and spindle bearings?
You may even need the quill itself trued up.

If you got the machine for free and had to do all this work it may still end up more expensive with lessor tolerance then a used bp on the market.

It’s definitely the more time consuming route.

True points -- I passed on this mill within about 2 minutes of seeing it in person. When I ran the table out to the end it was super tight and would not be useful. I threw an indicator on the quill which was clean and ran the table back to center and observed about .005" sag at center position despite the table being quite flat according to the 36" Starrett straight-edge i brought with (within a thou). I pretty much knew then it wasn't for me for all the points mentioned. As in life, when you imagine things, one tends to think optimistically but reality always pokes it head under the tent flap. I might take on a project like that at a different time but like I was saying 'restoration' isn't what I'm after. All told, it still wasn't a waste of time as the gentleman selling was an ex machinist and trades equipment like this frequently. He was up front about the condition before I went to go look for it and that's refreshing.

-Dave

bigwave · Mar 3, 2021

Rprecision said:
To me the spindle bearings are not outside the realm of DIY service and or minimal cost service.

Grinding and scraping the ways is not. Part is the cost of transportation to and from a reputable company. It certainly can be done, frankly its on my bucket list of learning, but not cost effective.

It's nice there are so many videos out there showing the process details and if you've got the time for the impractical art of laborious hand work, it can be very satisfying--it's my idea of 'meditation'. Similar to flattening a table top with hand planes and winding sticks. 'cost effective' isn't part of my equation as I'm a garage guy who does this for the satisfaction of hand-work but I make my money otherwise.

-D

AdamC · Mar 3, 2021

bigwave said:
True points -- I passed on this mill within about 2 minutes of seeing it in person. When I ran the table out to the end it was super tight and would not be useful. I threw an indicator on the quill which was clean and ran the table back to center and observed about .005" sag at center position despite the table being quite flat according to the 36" Starrett straight-edge i brought with (within a thou). I pretty much knew then it wasn't for me for all the points mentioned. As in life, when you imagine things, one tends to think optimistically but reality always pokes it head under the tent flap. I might take on a project like that at a different time but like I was saying 'restoration' isn't what I'm after. All told, it still wasn't a waste of time as the gentleman selling was an ex machinist and trades equipment like this frequently. He was up front about the condition before I went to go look for it and that's refreshing.

-Dave

What? Can you explain this a bit more? You are saying the table was flat but rose .005” at the ends due to what again? You are thinking the ways were worn .005”?

Not doubting you, but that seems extreme. Any chance the gib was loose or worn and the table was rotating in the saddle?

I don’t think I would, offhand reject a mill with .005” of surface profile one send to the other. Flaking can be .003” deep. Hopefully your measurement was done on a parallel or slip block to isolate that.

I guess my point is, ...or maybe it’s a question, no mill is perfect or perfect for long. How much wear is too much? I feel as tho a few thou of wear doesn’t directly result in a coupe thou of tolerance.

bigwave · Mar 9, 2021

AdamC said:
What? Can you explain this a bit more? You are saying the table was flat but rose .005” at the ends due to what again? You are thinking the ways were worn .005”?

Not doubting you, but that seems extreme. Any chance the gib was loose or worn and the table was rotating in the saddle?

Yeah, the table was sinking in the middle as compared to the ends. Seemed like wither the ways or the saddle were worn in the middle. Table action was smooth in the middle but super tight as I ran the table out to either end. On the leading edge of the table I used a straight edge to determine if the table was flat (not drooping). It was. I'm not sure how the worn gibs (or saddle) were but I don't see how gibs alone could account for such a deviation. In any case, I decided with the evidence I had and the knowledge of the gentleman selling, this was not the mill for me.

Cheers,
Dave

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