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Strategy question: leave the area under the headstock alone? Or scrape everything?

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
So, I finally have located enough parts to complete, I think, my personal Rivett 608, so it makes sense to get back to working on that when I have time. The bed needs to be scraped, wear, some corrosion, etc.

The question is about the headstock contact area. That area of the bed, and the corresponding part of the headstock, are presumably totally un-worn, and represent the original factory scraping and alignment. The side surface would be the same in the same area.

I hate to throw away that reference, but I am not sure it is even usable.

The bed is worn, to the extent of maybe a few thou on the top, but considerably more on the side dovetail.

If I scrape the entire thing, I probably need to use the headstock as a gauge, and then possibly touch it up as well. That would lose all the original references, for what that is worth.

But, I am not sure how I could use the original surface under the headstock anyway, except as a known reference when checking vs a test bar held in it.

Because of the design of this bed, there are 10 surfaces to keep in alignment, the back, top surface 1, side surface 1 of the V , side 2 of the V, top surface 2, side surface 1, dovetail surface 1 side surface 2, dovetail surface 2, side surface 3.

Here is the end view, with the top of the right-hand vertical surface being the "back", and proceeding counter-clockwise from there.

bOTGDam.jpg


All 10 surfaces must be held in tight alignment, since they are all carriage contact surfaces. The carriage may need to be built up with one of the various means, likely turcite, but perhaps that won't be needed.

If I leave the headstock area alone, I can build-up the headstock with the parts I have obtained, and have another large section done. But getting the rest of the bed aligned with it looks like a problem. It would need to be aligned, but offset a few thou.:nutter:

If I scrape the entire top, then I must leave the headstock bare, since it will need to be scraped as well. But the entire bed top would be aligned with itself. The question is whether it is aligned with the sides, especially the carriage dovetail. It could be pretty easy to get the alignment "off" enough to require a lot of scraping on the side, messing up the dovetail, leadscrew, and feed rod (the leadscrew and feed rod are set into the bed, with no bracket, in the recesses at left).

The idea is to do as good a job as possible, given that I obviously have no access to the factory master jigs. To me it looks as though regardless of original reference surfaces, scraping the entire top at once is the best.

I don't know how I could use the original surfaces as a practical assistance, other than scraping a jig to them, and using that as a reference for re-scraping the entire top. That jig would presumably be either the headstock (used as-is), or the tailstock (scraped to fit the H/S area) or both.

Any obvious advantage one way or the other?
 
So, I finally have located enough parts to complete, I think, my personal Rivett 608, so it makes sense to get back to working on that when I have time. The bed needs to be scraped, wear, some corrosion, etc.

The question is about the headstock contact area. That area of the bed, and the corresponding part of the headstock, are presumably totally un-worn, and represent the original factory scraping and alignment. The side surface would be the same in the same area.

I hate to throw away that reference, but I am not sure it is even usable.

The bed is worn, to the extent of maybe a few thou on the top, but considerably more on the side dovetail.

If I scrape the entire thing, I probably need to use the headstock as a gauge, and then possibly touch it up as well. That would lose all the original references, for what that is worth.

But, I am not sure how I could use the original surface under the headstock anyway, except as a known reference when checking vs a test bar held in it.

Because of the design of this bed, there are 10 surfaces to keep in alignment, the back, top surface 1, side surface 1 of the V , side 2 of the V, top surface 2, side surface 1, dovetail surface 1 side surface 2, dovetail surface 2, side surface 3.

Here is the end view, with the top of the right-hand vertical surface being the "back", and proceeding counter-clockwise from there.

bOTGDam.jpg


All 10 surfaces must be held in tight alignment, since they are all carriage contact surfaces. The carriage may need to be built up with one of the various means, likely turcite, but perhaps that won't be needed.

If I leave the headstock area alone, I can build-up the headstock with the parts I have obtained, and have another large section done. But getting the rest of the bed aligned with it looks like a problem. It would need to be aligned, but offset a few thou.:nutter:

If I scrape the entire top, then I must leave the headstock bare, since it will need to be scraped as well. But the entire bed top would be aligned with itself. The question is whether it is aligned with the sides, especially the carriage dovetail. It could be pretty easy to get the alignment "off" enough to require a lot of scraping on the side, messing up the dovetail, leadscrew, and feed rod (the leadscrew and feed rod are set into the bed, with no bracket, in the recesses at left).

The idea is to do as good a job as possible, given that I obviously have no access to the factory master jigs. To me it looks as though regardless of original reference surfaces, scraping the entire top at once is the best.

I don't know how I could use the original surfaces as a practical assistance, other than scraping a jig to them, and using that as a reference for re-scraping the entire top. That jig would presumably be either the headstock (used as-is), or the tailstock (scraped to fit the H/S area) or both.

Any obvious advantage one way or the other?

The headstock only contacts 4 surfaces, right? The two top surfaces (which are in one plane) and the interior V faces.



-Phil
 
I don’t see the point in preserving it. You’ll have to adjust headstock alignment and height anyways. And it’s just going to be one more thing that everything has to be aligned with.
 
I just read this and it's late. I'll try yo help in the morning. I am curious on b the head and tailstock taper size? For the others reading this. here is the machine, right Jerry? Rivett 608 Lathe

Yes, that is the beastie.

Headstock takes 5C right in the spindle. That is similar to other modelmaker's, or clockmaker's lathes. (earlier versions took #4, or 4NS collets)

Tailstock is a Rivett special taper, corresponding to nothing else on earth. The blueprint for it has a note to "bore to gauge", but no dimensions. The gauge was scrapped with all the rest of the tooling 50 some years ago, and apparently nobody now has any dimensions or description of the actual factory taper, it would all have to come from measurements.

I will probably take a Cerro metal casting of the taper to measure, and make several blank tapers for it. They will then fit mine, but may not fit any other Rivett, depending on wear, etc.

The other option is to rebore the quill for MT2, or make another quill in MT2 if I have to.
 
I also have a 608 to scrape, someday.

My thinking has revolved around the internal V on the top- I expect it is the least worn area of the machine that extends the full length. After verifying that it is true, I am planning on starting with the 2 widest faces (top and side). I'd maintain parallelism with the side using the V way and for the top, I'd use a dowel pin sitting in the V way and sweep across it along the length. While also checking perpendicularity with the top. The internal dovetail faces and internal flats would all reference those 2 surfaces, or each other, pretty easily. And then, last, redo the internal V as it will need to be lowered a smidge.

Not 100% sure this would play out, just what I've been imagining in my head.
 
If you plan to "true" the whole bed, you will of course need to scrape the top and at that point, the area where the headstock was located is no use. It also means that in the end, you will have to scrape the headstock and tailstock to fit the newly scraped flat surfaces of the top, as well as the v. One strategy is that in order to fit the headstock to the bed after scraping, you might be able to get away with only doing one side of the v on the bottom. That would move the head either forward of back fractionally (depending on which side you choose), but probably would not make much difference. Just a thought....
 
If you plan to "true" the whole bed, you will of course need to scrape the top and at that point, the area where the headstock was located is no use. It also means that in the end, you will have to scrape the headstock and tailstock to fit the newly scraped flat surfaces of the top, as well as the v. One strategy is that in order to fit the headstock to the bed after scraping, you might be able to get away with only doing one side of the v on the bottom. That would move the head either forward of back fractionally (depending on which side you choose), but probably would not make much difference. Just a thought....

And it is a good thought, especially if the V happens not to be worn, which is very likely the case (it is stained, with what is often called "surface rust", but does not appear to have any visible pitting (nothing does). Only the tailstock (and of course the non-moving headstock) touches that, the carriage does not have any connection to it, so actual wear is unlikely to be much. I do not recall if it is scored, but scoring does not invalidate it as a reference.

That was my original idea of how to maintain a connection, and it may be the best. I had not considered the idea of scraping just one side, which may be possible, I do not yet know. I think both sides will need to be scraped just on account of the surface rust.

I had thought of using it as the reference and then after everything else is done to it, working it over to fit the H/S and T/S referencing off the newly scraped parts. If it can have just one side scraped, that better keeps the original reference.

You are correct, as the top must be scraped, the V will clearly have to be "touched" to deepen it by the scraped-off amount regardless. Doing only one side would be ideal.
 
I just read this and it's late. I'll try yo help in the morning. I am curious on b the head and tailstock taper size? For the others reading this. here is the machine, right Jerry? Rivett 608 Lathe

I finally will try to explain how I would do it: Now you are "rebuilding" the machine and if they built the machine correctly then you have an advantage over a builder as he has done all the alignments and they were correct when new. You have to follow the builders work and do not have to come up with a new plan.

I see this a lot on internet forums and in person when you have a really smart student or internet rookie and they try to re-invent the wheel so to speak. Now as you have said the surface under the headstock is original on the flats a center V. On a Lathe the extreme right end or tail stock end is not worn either. Your machine also has the front face that is also not worn on the ends. You will need a camelback straight edge to scrape the V's. I am assuming you have a surface plate long enough that you can scrape the flats on it. So each non worn end is the same heights and in the middle it is worn. So you blue up the plate and scrape both ends the same amount until the worn area blues up. Count the times you scrape as you will need to know how much you took off when you go to re-align the saddle to the original centerline or axis. I would scrape the V's the same way, scrape the ends down using the camelback straight-edge making sure not to scrape the edge toward you more then the bottom. You could make a wood frame so you can tip the bed over so the V ways are horizontal. Mount the bed on cross members set at 30%. Scrape both unworn ends until the middle hits.

Now the headstock is the same way. If it was right when it was new ---Im going to post it so I don't lose it.
 
The headstock if it was good when it was new I would want to test the spindle alignment with the spindle bearings. If it was good, then nothing will need to be done to it. The reason I asked about the spindle taper was so you could insert a ground test bar in it and when the head was sitting on top of your surface plate you could indicate it. Also if you needed to match fit the head to the bed you could indicate the test bar top and sides. I will scan some pages out of the Schlesinger book and include them. Page 10, 15, 16, 30, 53 (a&b)fig 8. or Connelly book page 301 through the next few pages. If you don't have a taper test bar you can make a fixture similar to the one on page 305 fig. 26.63.

I have made similar ones before by mounting a ground parallel on the face of the spindle and you run a threaded rod thru the spindle with a washer and nut on the end of the lefts side of spindle. The precision ground parallel has a threaded hole on the side attached to the spindle face and I would bet you have a precision blade square say 6" long? If not buy one. Then on the outside or TS side of the ground parallel drill and tap 2 holes on that side so you can clamp the square to the parallel. You have already spun the parallel and shim one side if needed so the parallel outside ends indicate zero - zero as you rotated it. It will be on the same axis as the spindle bearings. Once you have mounted the square to the zeroed bar you can check the top and side to check the head alignment on a surface plate and then on the machine. Again if it was good from the factory it won't need much scraping. I hope you can get what I wrote, if not call me. 651-338-8141 Rich
 
Thanks.

I have both the book and a longer straightedge along with smaller ones..... and several flats, squares, a "Kingway" type device, indicators, etc although not a flat big enough for the entire bed.

My concern is that the side features must also line up well enough that very little scraping needs done. This because they are much harder to scrape.

As I think about it, they actually seem to be what should be the controlling features, since they have the most complex geometry, and are the hardest to fit, the hardest to scrape if much needs to be done. I think I would prefer to align the top surfaces to them, as opposed to aligning them to the top features. The top features are all open and accessible if more material needs taken off (which I hope to avoid, as I am doing this by hand).

I will look some more at this and see. I like the approach you mention, as it is along the lines of Connoley, etc.

The kicker here is the sheer number of surfaces that need to be aligned, on top and both sides of the bed. It appears some practical modification to the process may be required.

Overthinking? Maybe. Reinventing the wheel? That I do not think I will be doing. I have done most of this stuff before, it is the odd geometry here that poses the issue. I have never scraped-in anything with as much that all needs to come into alignment at one time.

The factory doubtless had a jig arrangement to get it ground to very close, checked with a special gauge, and scraped as a "touch-up".
 
Jerry when I write on here I figure I am writing to a million people. I didn't mean you would try to re-invent the wheel. As I said you have to assume it was good when it was built and you should be able to check much of it and it may not need scraping. I'm not there, I have to guess at most of this. If you like the front and it's not worn, of course use it as the master. The tops ends are probably like new so you can just scrape them straight down and get back to the new geometry. You need to check everything though. Good luck.. Rich
 
Quite a while back I rebuilt a Rivett 608pv lathe.
It was quite a challange to get it right as there are so many contact surfaces.

As I recall, scraping the top of the bed was the least of the job. The slide for the carriage is carried in a dovetail way on the front face of the machine, and from the couple I have seen this is one of the worst wear areas on these machines. The gib on the carriage wears and the whole carriage starts to twist and wears the dovetail in the bed.

The process I would recommend is as follows:
1) scrape the face of the front surface flat,
2) Scrape the top of the bed flat and square to the front face ( these can be done using a surface plate as reference)
3) scrape the bottom dovetail straight and parallel to the top of the bed
4) scrape the top dovetail parralel to the bottom dovetail.
5) Scrape the carriage to fit the slideway, and make a new gib for the carriage. It will probably need one.
6) Scrape the headstock tongue to fit the groove in the bed. Provided that you did not need to remove much off the top, you could scrape the back of the tongue only and the headstock will settle down nicely. Do the same with the tailstock.
7) The cross slide way is actually attached to the face of the carriage, and does not bear hard on the top of the bed. Depending how much you had to take off the bottom of the front dovetail, you might have to scrape the bottom of the cross slide way to get the mounting bolts to fit into the cottage.
8) scrape the cross slide and compound as usual.

I found the iron in the bed that I did was quite soft, and scraped easily.
The biggest challange is keeping the geometry correct.
The tailstock taper is actually a Jarno ( can't remember the number) I measured a number of original pieces and had a drawing for it. The only real question is what is the gage line diameter. A guy should be able to figure that pretty easily.

I think there might be a post of mine with some pictures here somewhere. I'll try to find it.
These are great little lathes, just not for ham-fisted bastards like me ;-))
Good luck

Peter

BTW- I think that the factory ground the beds, at least on the later machines ( mine was a 1944) The scraping was decorative, and for oil retention.


Couldn't find the thread with the in progress pics, just this one with the finished job
https://www.practicalmachinist.com/.../fs-rivett-608-lathe-174896/?highlight=rivett
 
Last edited:
The biggest challange is keeping the geometry correct
.
.
BTW- I think that the factory ground the beds, at least on the later machines ( mine was a 1944) The scraping was decorative, and for oil retention.

Been biting my ton... keyboard, but...

This is the LAST lathe on Planet Earth I would consider a suitable candidate for hand scraping, not just oil retention/distribution "flaking".

it's the complex geometry thing.

No harder that any OTHER multi-surface lathe for he with a bedway grinder and flexible head. One setup. INHERENTLY all surfaces come out congruent. That's what bedway grinders (and planers..) JF DO.

WAY harder to keep all those congruent by hand.

Page Two:

It is small and light enough to crate well, and ship R/T affordably.

The grind shop (or planer) need not be local. Schmeide doesn't have to operate in the high-rent, high tax, high labour cost, LA basin. They have good pricing, and they know their bizness.

Have it ground!

Put the labour of love into fitting the HS, TS, saddle, cross.. compound.. with good hand scraping skill.

That's a lot of work in its own right. There will be no shortage of challenges!

:)

But at least the "master", the "bedrock" if you will AKA bed ... without the "rocks" ..will be "right".

All else can then follow with confidence rather than angst .....and FAR less risk of disappointment.. even "do-over".

You want to enjoy running a damned fine lathe before you clock-out for the last time?

Or make a career out of trying to see if you are a good enough scraper to walk on water deeper than a quarter of an inch?

Fitting all the REST of it back to a pristine bed will be MORE than proof enough!
 
Been biting my ton... keyboard, but...

This is the LAST lathe on Planet Earth I would consider a suitable candidate for hand scraping, not just oil retention/distribution "flaking".

it's the complex geometry thing.

No harder that any OTHER multi-surface lathe for he with a bedway grinder and flexible head. One setup. INHERENTLY all surfaces come out congruent. That's what bedway grinders (and planers..) JF DO.

WAY harder to keep all those congruent by hand.

Page Two:

It is small and light enough to crate well, and ship R/T affordably.

The grind shop (or planer) need not be local. Schmeide doesn't have to operate in the high-rent, high tax, high labour cost, LA basin. They have good pricing, and they know their bizness.

Have it ground!

Put the labour of love into fitting the HS, TS, saddle, cross.. compound.. with good hand scraping skill.

That's a lot of work in its own right. There will be no shortage of challenges!

:)

But at least the "master", the "bedrock" if you will AKA bed ... without the "rocks" ..will be "right".

All else can then follow with confidence rather than angst .....and FAR less risk of disappointment.. even "do-over".

You want to enjoy running a damned fine lathe before you clock-out for the last time?

Or make a career out of trying to see if you are a good enough scraper to walk on water deeper than a quarter of an inch?

Fitting all the REST of it back to a pristine bed will be MORE than proof enough!

Well, I think you're mad as a mongoose but I'll give it to you - you seem competent, very intelligent and with a good deal of engineering common sense. I hope the OP will consider your advice but chances are slim given the amount of frightening BS spun here.

Keep well and keep posting !
 
Well, I think you're mad as a mongoose but I'll give it to you - you seem competent, very intelligent and with a good deal of engineering common sense.
Product of a deprived childhood, actually.

Dad was an Engineer.. for the Corps of Engineers.. which led to a decent retirement.. but not a lot of money whist earning it.

We were so poor, there wasn't money enough to spare for any OTHER kind of sense BUT "common".

:D

I hope the OP will consider your advice but chances are slim given the amount of frightening BS spun here.
Oh, he just may do. Low shipping mass and modest size are a big "enabler" vs a "heavy" lathe that can cost more in R/T freight than even an EXPENSIVE regrind.

Annnnd..

Long while ago King Richard got to salivating over how he'd LOVE to scrape on that particular Rivett!

Too EAGER by half!

And J and I figured, surely he would! At his hourly rate? ..and until it was down to about half its as-built mass!

:)

Scary, that!

Also kind of a warning that given multiple planes? It was, in fact, NOT as easy as most other lathes.

And the more yah scrape? Especially if having to "correct" a false move?

The HARDER, not easier, it becomes to fit the OTHER bits back to to the final product w/r the "reshaped" bed.

As happens? THAT part - the various component fit-ups - is FAR from a "trivial exercise" on a Rivett. Most especially if the bed has NOT been first made "as good as can be".

I think Shapeaholic nailed it. Rivett would have HAD to do a superior job of grinding. Leaving nought BUT hand-flaking.. Or they'd not have been able to get the complex bit of kit off their own production floor!

Grinder? Setup is a tad more complex. But once done? Ignorant electricity does the tiring part. The grinder don't actually GET tired and forget what it is doing.

And the bedway does the alignment. What's not to like about THAT?

Why.. that's so f*****g USEFUL that if planers and bedway grinders did NOT already exist? Some bright spark would prolly INVENT one!

Go figure...

:D
 
The tailstock taper is actually a Jarno ( can't remember the number) I measured a number of original pieces and had a drawing for it. The only real question is what is the gage line diameter. A guy should be able to figure that pretty easily.

jarno taper is about the easiest as ever was. Pity Oscar did not manage to get wider acceptance of it. "The problem is." that it isn't hard to find LARGER jarno goods, used-but-good. I have several 12 Jarno DC for the 10EE's from Grand Tool that were "NOS" but.... the boxes and waxed protective paper had been keeping a shelf from blowing away in the breeze...since the Second World War!

Smaller ones are harder to find, used. OTOH, whilst HS "partial section" tapers are more the rule than the exception, I'd expect even Rivett to have done a TS to "stock" jarno, full-sized, for whatever jarno number they utilized.

#6 may be the one?

Riten still makes the whole jarno size-range new. They also regrind DC & rebuild "live" centers.

Item # 72063, Dead Center Series 6 Jarno Taper Carbide Tipped 6.00 Inch (in) P - Overall Length Full Center On Riten Industries Inc.

So do Stark:

Jarno Taper Standard

Shanks for jarno to Jacobs Taper or such? I haven't even looked. Jarno is mostly found in spindles, rather than a TS. Either of the above probably have them at least as a CAD in their files so they can make them when asked.
 








 
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