Headstock Alignment Factory Provisions.

[opensourcefan]

So as a follow up to my 8x16 lathe headstock being out of alignment; I've come to the conclusion that I will need to recut the "V" on the headstock to allow room to move it without lifting up on the bed V. Right now if I shim it there's no room for the side to side movement and it lifts the headstock which in turn requires shimming in the rear to counteract the lift.

If I'm going to do some mods, I'm curious if I can build in a common method that some lathes incorporate for such adjustments. I just don't know what is used or what might fit on a smaller headstock.

I like the idea of putting it on a centering post that I can rotate about with some adjustment screws or something.

Anyone have any photos or ideas of what I can incorporate onto this?

 

[Susquatch]

So as a follow up to my 8x16 lathe headstock being out of alignment; I've come to the conclusion that I will need to recut the "V" on the headstock to allow room to move it without lifting up on the bed V. Right now if I shim it there's no room for the side to side movement and it lifts the headstock which in turn requires shimming in the rear to counteract the lift.

If I'm going to do some mods, I'm curious if I can build in a common method that some lathes incorporate for such adjustments. I just don't know what is used or what might fit on a smaller headstock.

I like the idea of putting it on a centering post that I can rotate about with some adjustment screws or something.

Anyone have any photos or ideas of what I can incorporate onto this?

Wow..... Thats a major undertaking that I'm not even sure I would trust.

The three methods I've seen most often are:

1. Shims in the right places
2. Bending the bed or frame with the levelling screws
3. Machining everything as close as possible in the first place (ie no adjustment practical).

If your lathe uses the first or second method, just have at it.

If your lathe uses the third method, which you have led me to believe is the case, I'd either give up and accept its limitations or I'd do a extensive analysis of the structure of the head and bed to see if I could find a way to do a bit of either 1 or 2 or both. Don't neglect the possibility of reverse bending by loosening or tightening existing screws

Can you take some closeup pictures of how the head and bed mate up?

 

[opensourcefan]

How it currently attaches is quite simple so it's not that major really. The front bed V seats into a V channel in the headstock casting. That's it along with four through bolts into tapped holes in the bed. The rear bed way is just a flat mating surface.

Shims is what I am doing but it wasn't designed for it so there's no room for movement. Because it's a V, the only way to move is up while moving to the side.

Option 3 is what I will try at first of course as this is how it was supposed to be. But I'm not holding out faith as attention to detail when building this thing didn't exist.

I'm not going to just live with it, I will make it better. I'm not convinced that any lathe that suites my meager needs will be free from defects so I may as well tune this thing up. I like the size.

 

[140mower]

Have you tried running a fine stone over the surfaces and see if there's a small burr or something kicking it out of alignment?

 

[opensourcefan]

Have you tried running a fine stone over the surfaces and see if there's a small burr or something kicking it out of alignment?

No, Haven't pulled the head completely off yet.

 

[140mower]

I think I would start there, these offshore machines and attachments are kinda famous for leaving the factory a little rough around the edges. Stone, deburr, clean and reassemble and I suspect that you will be closer....

 

[Susquatch]

Shims is what I am doing but it wasn't designed for it so there's no room for movement. Because it's a V, the only way to move is up while moving to the side.

Assuming I understand you, the head sits on the bed just like a tailstock does but without the ability to slide back and forth because it is bolted down.

If so, then the shim could be used like a saddle over the V thus imparting no side thrust - just vertical. It would also require a thicker shim on the flat to maintain even side-to-side lift. Or if you also need twist, perhaps deliberately different lifts.

Edit - I agree with what others added while I was writing my post. A light stoning is appropriate. Wouldn't that be nice to find a high spot that could be just stoned away?

 

[opensourcefan]

Yep and yep. That is what led me into trying something else since that will be a lot of shimming leaving little contact with the ways unless the shims are full length.

Thinking maybe an adjustable V grove in the headstock.

Really just curious what options lathe manufacturers have used. I haven't been around enough to know, can't really find much documentation on headstock attachment out there.

 

[Susquatch]

And one more add - don't forget to look at the head ways too. Lots of places for a burr or a tiny piece of metal (or other stuff) to hide.

 

[Susquatch]

Yep and yep. That is what led me into trying something else since that will be a lot of shimming leaving little contact with the ways unless the shims are full length.

Thinking maybe an adjustable V grove in the headstock.

Really just curious what options lathe manufacturers have used. I haven't been around enough to know, can't really find much documentation on headstock attachment out there.

Can you remind me how much it is out and in which direction? You prolly said that already but I couldn't find it with a quick scan whereas you prolly have it burned into your brain.

A full length shim will tilt the head forward toward you or backward away from you but won't change its nod.

 

[Susquatch]

Really just curious what options lathe manufacturers have used. I haven't been around enough to know, can't really find much documentation on headstock attachment out there.

Here is a quick summary of what I have seen:

Head bolted to the left side of the bed - what I have.

Most common is Head sitting on the ways (prolly what you have).

Head bolted down to a flat section beside the bed.

Bottom half of head cast integral with the bed.

One piece lower half head with the bed bolted to that.

Prolly lots of other ways to do it, but that is what I have seen.

 

[opensourcefan]

Can you remind me how much it is out and in which direction? You prolly said that already but I couldn't find it with a quick scan whereas you prolly have it burned into your brain.

A full length shim will tilt the head forward toward you or backward away from you but won't change its nod.

It's approximately .005" over 3" in length. The end of a bar is closer to the operator. I've placed .004" of shims on the inside of the V way forcing it to twist away from the operator. That required 0.002" of shimming in the rear to bring it back to level.

It's about .002" runout now over 4" still towards the operator, however level is bang on.

If I was to use a full length shim it would need to be tapered.

I appreciate all the methods you provided, thank you.

 

[Susquatch]

It's approximately .005" over 3" in length. The end of a bar is closer to the operator. I've placed .004" of shims on the inside of the V way forcing it to twist away from the operator. That required 0.002" of shimming in the rear to bring it back to level.

It's about .002" runout now over 4" still towards the operator, however level is bang on.

If I was to use a full length shim it would need to be tapered.

I appreciate all the methods you provided, thank you.

Wow, 3am...... And I thought I was bad for that kind of thing!

Good morning to you when you read this!

I'm impressed with your results. You have managed to eliminate more than half the misalignment.

In so doing, I assume you have ascertained how much, where, does what. I also assume that your tie down bolts are tight when you do your measurements.

And of course, I assume you didn't find anything wrong with any of the ways. That's really too bad. I had really high hopes that a burr or a wayward chip at the factory was the source of all your problems. When @140mower suggested that possibility, my mind latched on to it. It just seemed so obvious that this is what happened. 5 thou over 3 inches is a LOT!

Since it is now level, but still pointing inward, it sounds like you will have to shim it in pairs from now on to avoid changing level - one at the front of the V-way on the left and the same size on the rear of the V-way on the right. The good news is that you won't be further stressing the head casting that much in doing so. I confess that I have been worried about that - again, 5 thou over 3" is a LOT!

But saying that also makes me wonder about your top & bottom gear box casting alignment. Is it possible that the top casting (which holds the spindle) is twisted inward relative to the bottom casting (which sits on the V-Ways)? I hope that isn't the case because they are often pinned to prevent that possibility.

 

[Rauce]

As an extra check you could blue the headstock and see how well its contacts the flat surfaces and the V that it sits on. This would give you an idea of how well it is fitted right now.

I'm not familiar with any lathes that have features for adjusting headstock alignment after it leaves the factory. What I've seen is some kind of feature that keys the headstock into a fixed alignment with the bed with the alignment set at the factory.

There are epoxy type products that are specifically designed for this type of application. One would rough mill the female V in the headstock to get clearance for alignment, set it in position and then inject epoxy to fill the space. Release agent would be on the bed so the epoxy bond to the headstock side only.

 

[Rauce]

Here is a link to the application manual from Devitt Machinery in the US. They are a distributor for epoxies used in Machine building and re-building.

http://manuals.chudov.com/Moglice-Epoxy-Application-Handbook.pdf

For a static alignment application the product I think you want is DWH 310 FL ("has steel fillers and is often used to produce bearing seats, align
ball screws, align columns to beds, locate hardened seats in identical pallets, etc"). If you contact them I'm sure they will discuss your application and guide you through what products you would need.

 

[Susquatch]

As an extra check you could blue the headstock and see how well its contacts the flat surfaces and the V that it sits on. This would give you an idea of how well it is fitted right now.

I'm not familiar with any lathes that have features for adjusting headstock alignment after it leaves the factory. What I've seen is some kind of feature that keys the headstock into a fixed alignment with the bed with the alignment set at the factory.

There are epoxy type products that are specifically designed for this type of application. One would rough mill the female V in the headstock to get clearance for alignment, set it in position and then inject epoxy to fill the space. Release agent would be on the bed so the epoxy bond to the headstock side only.

The beauty of an epoxy "shim" is that it can be full length so stressing the head casting is not an issue.

The downside is the challenge of trying to get it right the first time. Not confident that this is within the skill sets of mere mortals like most of us.

 

[whydontu]

I would think the epoxy would be relatively easy to do. Shim to suit, crazy glue the shims to keep them in place, squoosh in epoxy and tighten down the clamp bolts to extrude the excess epoxy. Scrape of the excess, some masking tape to hold the epoxy in place until it cures.

 

[opensourcefan]

I confess that I have been worried about that - again, 5 thou over 3" is a LOT!

Yes, I noticed it when I was trying to make a close tolerance but short part. Brutal, never expected that.

There are epoxy type products that are specifically designed for this type of application.

That is a great idea. That's about 99% prep and 1% squeeze. Making sure everything is perfect prior to void filling. I do like the idea of it creating a larger seating surface though.

 

[opensourcefan]

On a side note, how sufficient would 4 bolts mating two flat surfaces be for a headstock? No V seating or anything else, just two surfaces stuck together with 4 bolts in slightly oversized holes holding it together.

 

[opensourcefan]

Wow, 3am...... And I thought I was bad for that kind of thing!

Lol, sorry if I woke you. Good morning to all. My shift working has never coincided with normal people.