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darryl
12-09-2011, 03:01 AM
We all hear about aligning the headstock, etc, but what about the alignment at the point where the headstock is 'made'? Just wondering if anyone here has done this, or seen it done- I'm talking about the factory taking the headstock casting and aligning it on whichever machine it is, then boring for the bearings, etc. Somewhere along the line this initial 'precision' is built in. Anybody know of a video showing this being done?

Davo J
12-09-2011, 03:41 AM
I would say it is done on a horizontal boring machine. My Chinese lathe come with a flat base on the headstock, so it would be easy to mount on a table to do, and as long as it's bored correctly horizontally it can be adjusted when mounted on the lathe.

I am not sure but with the other type of lathes that are aligned by the lathes ways running right under the headstock, they might have a fixture made up to go onto the boring table to align it while getting bored.

I hope you do get a link, as I would be interested as well.

Dave

.RC.
12-09-2011, 05:13 AM
http://pounceatron.dreamhosters.com/docs/radial-drill-as-jigbore-pacemaker-headstock.jpeg

Richard Wilson
12-09-2011, 06:36 AM
We all hear about aligning the headstock, etc, but what about the alignment at the point where the headstock is 'made'? Just wondering if anyone here has done this, or seen it done- I'm talking about the factory taking the headstock casting and aligning it on whichever machine it is, then boring for the bearings, etc. Somewhere along the line this initial 'precision' is built in. Anybody know of a video showing this being done?

I don't know how its done now, but I've seen a photo of boring the headstock for the bearings, taken in the Raglan Engineering works (UK c 1950)
On those lathes, the headstock was integral with the bed, and the method used was a fixture carrying the boring head, sliding on the bed ways, so alignment was absolutely guaranteed.

Richard

alanganes
12-09-2011, 07:16 AM
On those lathes, the headstock was integral with the bed, and the method used was a fixture carrying the boring head, sliding on the bed ways, so alignment was absolutely guaranteed.

Richard

If you read the Gingerly building-a-metal-lathe book, this is the method he uses. I liked that book even though I had no intention of building a lathe with his methods. It gives a pretty good glimpse into how one develops the alignments and such that build the accuracy into the machine.

justanengineer
12-09-2011, 08:16 AM
I believe there is an old photo within the South Bend factory in the 20s or 30s showing a very similar method of "on lathe" boring of the head and tailstocks.

Bazz
12-09-2011, 08:32 AM
In the old day they bore the hole any way they could and plane the bottom in a planer

the headstock and the tail-stock was located by the center hole in a jig and machine in the same time

If you bore the headstock using the bed to insure the alignment you may be able to machine the bearing hole but every other hole will have to be machine accurately using the spindle bore for reference, that is not a very good way to do production

J Tiers
12-09-2011, 09:24 AM
Seems as tough ir would be better to get the alignment close, but have all the headstock holes in their correct relative alignments. Then planing/milling & grinding or scraping would align the whole thing to the bed.

justanengineer
12-09-2011, 09:58 AM
http://www.lathes.co.uk/southbend/page16.html

5th pic down shows a batch of headstock castings having the bed mating surface gang milled. Spindle bores are evident, though I dont know if they are cast that way or if finish machined already.

http://www.lathes.co.uk/southbend/page18.html

Last pic shows a tailstock bore being machined on a modified lathe (knew I saw a lathe doing it somewhere). Cannot tell if the bed mating surface is already machined, but doubt it after thinking about it awhile.

loose nut
12-09-2011, 12:53 PM
Myford had special ML7 lathe beds set up to do just that.

The headstock casting would be machined and close fitted to the bed and then a special boring head mounted on the saddle would bore out the headstock. That way one headstock would fit any bed without adjustment. Modern cheaper lathes usually have an adjustment feature that will fit the headstock accurately????? to the bed.

Mcgyver
12-09-2011, 01:17 PM
given how many lathe manufacturing plants there in North America, there is going to be shortage of experts qualified in this subject. So with far less qualifications that expert status requires, I'm familiar enough with it to have a good sense of it through extensive discussions and meetings with the last manual lathe maker in NA, same with machine tool rebuilders, and also discussions here and PM with the guys who've done it.

The headstock is machined and with the spindle installed, it is scraped to the bed. A rod us affixed to the spindle so that can be indicated by moving the already scraped carriage along the bed. The manufacture will use precision ground test bars that mount in the spindle, however it is not imperative to have the test bar either concentric or aligned - you can measure this error and compensate - ie if you indicating a cone because test bar axis isn't perfect to spindle, get the cone centred and the headstock is aligned

needless to say the lathe has to be perfectly levelled so there is no bed twist. This entire process of scraping the headstock in also something you have to do after grinding or scraping the bed

loose nut
12-09-2011, 05:11 PM
I doubt that any lathe manufacturers scrape in much of anything anymore.

Bob Fisher
12-09-2011, 05:36 PM
No expert here , but it seems that any lathe with "V" ways could be machined to fit a bed with the same "V" configuration. I have had the headstock off of my 10" Logan and it does not appear that you could assemble it wrong,since the "V"aligns it only in one direction. Works for me. Bob.

duckman
12-09-2011, 05:55 PM
The funniest thing is that every body's brand new machine is built on used machinery :eek: , had a customer argue with me that it wasn't true but then he realized that what I said was true. :D

Mcgyver
12-09-2011, 07:10 PM
I doubt that any lathe manufacturers scrape in much of anything anymore.

I've seen it....how else would you suggest its done? especially with a v way, its difficult to a proper mate between V and flat of the two components by just machining each, they need to be fit by comparison.

I don't doubt many low budget manufacturers don't do it that way, but its still done and is the correct way to achieve the desired fit and bearing.


No expert here , but it seems that any lathe with "V" ways could be machined to fit a bed with the same "V" configuration. I have had the headstock off of my 10" Logan and it does not appear that you could assemble it wrong,since the "V"aligns it only in one direction. Works for me. Bob.

Once fit, I agree, the V registers it. The trick is how did it get that way....the V and spindle axis perfectly aligned. That's where it is, or should be, scraped to the bed

you guys might not be thinking through the manufacturing of it - machine a V and flat, then machine the mate. try to get angle a perfect blue out between the mates while the flat is also perfect. and with spindle axis perfect. That is a really difficult machining task to get right, far easier to do the spindle bore then fit by comparison. also, every time they dress the wheels on the ganged lathe bed grinder its a slightly different configuration of V and flat. For a guy who knows how to scrape its not that onerous or time consuming. I have no idea how budget lathes are made, just pointing out that for a high end bearing fit and alignment scraping may well be the quickest route and is how its still done