Author Topic: Project 1: Taper attachment clamp  (Read 11510 times)

Offline AdeV

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Project 1: Taper attachment clamp
« on: December 01, 2009, 08:54:28 PM »
 :proj:

OK, this is going to be Lathe Project 1; mainly because it doesn't involve much lathe work! And lots of milling work, which I'm better at. At the moment...

Readers of my lathe thread elsewhere will be familiar with the problem; I have no way of locking the taper attachment to the lathe in order to actually cut a taper. Davo J suggested a device which clamps to the ways, and this is exactly what I will do. It also has the benefit of being a relatively straightforward job, which is nice for a beginner like me  :thumbup:

Now, before I get started, some excuses.... I'm not getting as much shop time as I'd like at the moment for a couple of reasons: Work, and the cold weather. The former is self explanatory; the latter means I can't do much work in their before my right hand turns into a world of pain. It's a sort of RSI type thing (25 years of bashing on computer keyboards, or nearly 70% of my life, and I STILL can't touchtype with more than 2 fingers); basically, I lose all strength in the hand & the whole back of the hand just gets more & more painful. Which is bloody irritating, pardon my french. I may have to try some fingerless gloves to see if that cures the problem.

Oh, and the other thing, I got a bit of brass swarf in my index finger, and boy does that sting.  ::) Expect it to be a few weeks before it's all finished...

Anyway, excuses done, here's the plan - And pretty well straight away I need advice:


That bit should be self explanatory. I'll thread the end of some stainless bar so it goes as far into the taper unit as possible. The bars will probably be about 8" to 10" long, in total, I don't think they'll need to be longer. There's only so far I'd want to wind the carriage back along the taper, after all.

I've then come up with two possible designs for the actual clamp unit. I envisage each one using between 4" & 6" of space along the ways; and will be deep enough + a bit to catch both sticky-outy-rods. I will probably make it from a lump of steel (milling out some material if it's too heavy); or I'll get the welders to rough one up out of thick steel plate & then mill it to size.

I don't have any C-o-C facilities here (no scanner or camera @ home), so I had to use some real cad. Fortunately, I took screenshots to keep that C-o-C feel. And there's no dimensions either... :hammer:

Option 1:

A (in red) represents the cross-section of the lathe ways. I have around 1/2" underhang on the left-hand-side (inside edge), and about 5/8" on the outside edge - but I can't use both underhangs at the same time, only one of them; otherwise I'd have to remove the tailstock to fit/unfit it, and the tailstock couldn't be brought forward past the clamp.

B (in white) is the taper clamp, as seen from the side. The dodgy yellowy bit is a gib strip, either in brass or steel, TBA. The green bolt (C) clamps up against the gib strip & pulls the taper unit onto the backside of the ways. There'll be two bolts, I think, to even the load on the gib strip & maximise the holding force. Any slippage could be disastrous to both the material being cut, as well as the cutter & maybe even the lathe itself. So slippage must be avoided at all costs. Note that "B" is shown using a fair amount of the underhang on the outside of the way; I don't think this would be possible whilst retaining a snug fit on the ways, so I'd use the inner underhang (as a "hook") instead.

Moving on, the two stainless bars sticking out of the taper unit fit through the almost invisible holes D (in blue). Bolt F (cyan) clamps the holes by pulling slot "E" (pink) closed. Again, there'd probably be 2 bolt F's. Later on, I will replace the bolts with handles, but as I can't draw them in AutoCAD, it's a fair bet I can't make them yet either...

Advantages: it will clamp the ways really firmly, and since neither face is a sliding face for anything on the lathe, it won't add any wear or warp even if it's really scraunched down.

Disadvantages: It may interfere with the tailstock (but perhaps I could avoid that by using longer bars, allowing the tailstock to be moved inboard of the taper clamp); it looks very difficult to machine with just a mill; maybe making it in 2 bits & silver soldering them together would make it easier, but would it retain enough strength?

Option 2:

This works in exactly the same way as the one above. Even the letters and colours match. Woo.

Advantages: Much easier to machine; tailstock can be moved past the unit as shown, so it could be left permanantly attached (just unclamped to the ways in normal use)

Disadvantages: Less clamping stability, there would be a tendancy for the clamp to try to twist as the carriage moves backwards & forwards. The top clamping surface is also the slide for the carriage, so it's a wear surface & is covered in oil (which will reduce the clamping effect).

There's a couple of things I can do to this one to help mitigate the disadvantages: I could use a little bit of that slot (not much, as the tailstock also uses some of it) to provide a "hook"; but I'd have to put the gib strip & clamp bolt on the underside, so the lip that goes into the slot is pulled into it, rather than being pushed up out of it (as would happen with the current design).

On balance, I prefer option 2 for the simplicity & the fact I can leave it on the lathe most of the time; but I'd appreciate people's thoughts as to how well it's going to clamp onto an oily & smooth surface. If the danger of slippage is too great, then it will have to be option 1.

Gents - if it were you making it, would you do option 1, 2 or 3 (which I haven't thought of)? Your input will be very much appreciated  :nrocks:
Cheers!
Ade.
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Offline kvom

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Re: Project 1: Taper attachment clamp
« Reply #1 on: December 01, 2009, 09:38:24 PM »
I had to make mine as well (Monarch 10EE).  I replicated the original Monarch design as much as possible.  As your ways have a similar profile mine would work for you as well.  The clamp is two pieces.  The heavy main piece has a lip that fits the space between the flat and V ways.  The clamp part is similar to your 2nd drawing except it is a piece of aluminum that bears on the bottom of the square way.  The clamp bolt passes through the main part from the top.

The Monarch has only a single bar that connects the TA to the clamp.  It passes throughn a horizontal hole bored in the clamp, is threaded on both ends, and two bolts are used to secure it to the clamp.


Offline sbwhart

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Re: Project 1: Taper attachment clamp
« Reply #2 on: December 02, 2009, 01:43:53 AM »
Hi

Nice intro to project  :thumbup:

I'd go for option 2 with a little hook added that goes into the way groove as shown in Kvom's pic

Have fun

Stew
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Offline Davo J

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Re: Project 1: Taper attachment clamp
« Reply #3 on: December 02, 2009, 04:39:38 AM »
I agree with Stew, if not go with your option 2. If you went with Kvom's idea but wanted to make it all out of solid like your pictures,you could slide it on from the end of the bed and it would be semi locked in place.
I would love a taper attachment on my lathe, maybe one day?
Dave

Offline AdeV

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Re: Project 1: Taper attachment clamp
« Reply #4 on: December 02, 2009, 08:20:29 AM »
Thanks kvom, I like the idea of the underside pulling up; it gives me the best of both worlds - an accessible bolt/handle, and a pull-down clamping action.

I did a bit of measuring, and I've got just about 0.100" width of that slot that I can use before fouling the tailstock; I can go slightly oversized on that & fettle it to fit, as the more meat the better on that bit. By keeping to that dimension, I can leave it clamped to the taper attachment more or less permanently, unless I'm turning a really long bar & need the carriage right at the end of the bed.

This is the new design:


This now works in exactly the same way as the kvom/Monarch version, bolt C pulling up the unlabeled yellow piece (ali, brass or steel: I haven't decided yet). Also, as I don't have a slitting saw, I've changed the clamp to work in the same way. The bolts are shown here with the thread at the top end; in fact, they'll be plain shank all the way through piece B, with the threads only being used to draw the yellow clamping parts up. One last difference; bolt F will draw against a flat, not a slope as shown here... and it'll be centred between the circular cutouts so it clamps each one with approximately the same force.

Interestingly, the Edgwick page on lathes.co.uk almost shows enough of the taper attachment; what is interesting is there's clearly a single very long bar sticking out of the back of it, as can be seen here, indicated with the blue arrow:


(picture credit: http://www.lathes.co.uk/edgwick/page2.html)

Unfortunately, the clamp, whatever it is, is not shown - or maybe it's hiding behind the tailstock.
Cheers!
Ade.
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Offline Davo J

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Re: Project 1: Taper attachment clamp
« Reply #5 on: December 02, 2009, 09:00:31 AM »
If you wanted to use the rod idea you could make somthing like this to go on the taper attachment. Most attachments I have seen have a single rod.
Dave

Offline kvom

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Re: Project 1: Taper attachment clamp
« Reply #6 on: December 02, 2009, 12:28:45 PM »
I would try to use the full width of the slot in the way.  The little tongue is the part that breaks off on the Monarch clamps (cast) and is the reason that the clamp goes missing on many 10EEs with TAs.   If you make the clamping rod long enough you can position the clamp itself to avoid the tailstock.  Given that the TA is used infrequently, you will likely find it convenient to remove both the rod and the clamp when not in use.  For mine, I machined the clamp first and used the rod itself to position the through hole.

On the 10EE, the rod can be attached to the front of the saddle for cutting tapers near to the tailstock end.  You might check if there is a matching hole on the other end of your saddle.

Offline AdeV

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Re: Project 1: Taper attachment clamp
« Reply #7 on: December 09, 2009, 05:07:28 PM »
I managed to snatch a couple of hours in the shop tonight, Plus, some new toys turned up:

In particular, I needed the 3MT-2MT sleeve, as the one I was using was knackered & allowed about 1mm of vertical slop. Not good when setting tool heights. The new one is as tight as a duck's bum... That red tool is an old one, it's there to show the typical tool size on my lathe, versus the size of thread cutters I bought from RDG. OK, I knew they were going to be small, but aaaaaah, so dinky! That would also be be a pain, as you will see.

So, today I thought I'd try a thread. My first with the proper tool... I've got some rough mystery-steel bar (which has been subject to several lathe-and-mill-related experiments), the end of which was already cut down to somewhere near the diameter I wanted, so it'd only take a few cuts (0.100" off the diameter, as it happened) to bring it to size. Experiments earlier today revealed that taper attachment takes 3/8" Whitworth bolts. The Whitworth tool is the thin one in the picture above.

First job, then, cut down the bar. I have it in the chuck, with the live centre to keep everything in line (no traveling or stationary steady, yet). I've actually got way too much sticking out of the chuck, but I figured I was only going to be taking light cuts, so I'd get away with it. So, the first thing I did was bash my last decent carbide bit against the edge, breaking it. ARGH! Fortunately, I'd sharpened (ish) a HSS bit a while back & got that close to being on centre, so I used that instead. Here's the first 0.010" cut:



The black thing in my hand is the feed engagement lever. My other hand is pointing the infra-red remote control at the camera. Gotta love that remote control... Anyway, a few cuts & measurements were taken, and eventually I had the proper outside diameter (0.370", as measured from the test bolt).

Here we are a bit further along. The chips are a nice silver colour, and the smoke is light, so I'm happy with the speed & depth of cut:


Next up, I need to mount the threading tool. Unfortunately, it's waaay too low in the holder, if placed on the bottom:


Too high if the ali went underneath:


So, I decided to slot the ali block so the tool sat in it & sat at the right height. I must make that QCTP soon... So, over to the mill: The ali is a scrap piece I had, which is already squared off. So I lobbed it in the vice & found the back edge:


With the edge programmed into the DRO, and the width taken (0.940"), it was a simple case of mounting up the cutter, moving to the centre of the block, and touching off:


I chose to cut the slot full-width in one pass, mainly to save time. Fortunately, I have a decent set of metric end mills & collets, so despite the fact I work pretty well exclusively in Imperial, the slot width is 8mm (+ a gnat's c*ck). It needs to be 0.350" deep. The mill, bizarrely, has metric X & Y axes, but an imperial Z-axis. No idea why.

First cut was 0.100" deep, full length. It's in there, somewhere:


This'll find it:


After a few more iterations, and a couple of trips back to the lathe to check the height, and we're done:


Just need to lob it in the lathe, put some packing above (so the screws don't run out of room), and presto. The angle of the photo makes it look high, actually it's almost exactly bob-on:




So, FINALLY, I can cut my thread. This is the second pass, going about 0.010" deep:


I'm cutting with the tool square on to the work for two reasons; neither of them valid: First, because I've got the tailstock in the end of the work, I can't offset the topslide without the tool post fouling the tailstock; and second, I don't currently have an angle gauge, so I couldn't accurately align the tool against the work, having set the angle. Wheras, it's nicely in line, and the tool post clicks into place when used straight, so I know I've got the right angles. It just means I've got to feed slowly & carefully so as not to overload the tool. Several 0.0025" feeds later...:


What that picture doesn't show is the near disaster that happened right at the end. Having taken the cut 0.030" deep, I checked the thread with a bolt. It threaded on, but only just; so clearly another few thou & I'd be there. But, somehow, I managed to bollix up the dials, and whilst i've no idea how deep the cut was that I started taking, it was WAY too deep. Rather than stop, I backed the cross feed out slowly until the chip size seemed reasonable. And left it at that.

The result is OK; it's a bit sloppy at the start of the threads, but much better at the end of the threads:


And it screwed nicely into the taper adapter, yay!




That was all I did tonight. I ran out of time...

BTW, please tell me if I'm over-doing the pictures, or if I'm showing too many of the intermediate steps. As a newbie to the machining world, it's hard to know where to pitch a project like this. I expect for most of you this is like taking a stroll in the park? But me, I'm learning something new every time I stand in front of the machine... So, if I've got it wrong, please let me know so I can improve the write up.  :thumbup:
Cheers!
Ade.
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Offline kvom

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Re: Project 1: Taper attachment clamp
« Reply #8 on: December 09, 2009, 05:59:55 PM »
I think you'll want to attach the rod to the hole closest to the ways; it will be more rigid that way, and matches the picture.  On my Monarch the rod is quite long with a long thread on the tailstock end.  The rod passes through the clamp and is secured by jam nuts on either side.  That way you can position the clamp on either side of the tailstock.  The close the clamp is to the TA the more rigid the setup will be.

I have the same keyless chuck on my mill, and have been very happy with it.

Offline dsquire

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Re: Project 1: Taper attachment clamp
« Reply #9 on: December 09, 2009, 06:15:07 PM »
Adev

Nice job on that. I think the step by step and amount and quality of the photo's is just fine. Having a remote for the camera sure makes it nice. :ddb: :ddb:

Cheers  :beer:

Don
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and your better best

Offline AdeV

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Re: Project 1: Taper attachment clamp
« Reply #10 on: December 09, 2009, 07:04:33 PM »
kvom - I've not decided yet whether I'll stick with using both bolts & two rods, or use Dave's idea & fabricate a piece with a single rod coming out. Either way, I want the forces pushing straight into the taper unit.

I'd already bought a chuck just like that one for the milling machine, but that of course is wedged onto an R8 taper. At 25 quid, it's cheap enough to buy a second one for the lathe - and the quality is excellent.  :thumbup:


Don: Cheers m8 :thumbup: It's always a worry when posting lots of pictures; am I going too slow? too fast?

The camera is an old Olympus UZ-2100. It's only 2 megapixels, but it takes fabulous pictures (I can't take any credit - the camera really does do all the hard work). Great zoom lens too - 10x optical with mechanical image stabiliser. I saw one sell on eBay recently for about 40 quid - at that price, it's well worth buying one. Mine cost me nearly £800 brand new, back in 2000...
Cheers!
Ade.
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Offline kvom

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Re: Project 1: Taper attachment clamp
« Reply #11 on: December 09, 2009, 09:19:44 PM »
Looks like you'll soon be able to cut some trial tapers.   :thumbup:

FWIW, on my lathe I get better results cutting the tapers from the large to the small end.  Has to do with the TA pulling the cross slide rather than pushing..

Offline AdeV

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Re: Project 1: Taper attachment clamp
« Reply #12 on: December 10, 2009, 03:30:27 PM »
I had another go at the thread tonight, just to make sure it wasn't a fluke that I made it work yesterday. Pleased to report that it's not (a fluke, that is!):




This one's a much tighter fit on the threads; I'm not sure if that's because the OD or ID is incorrect, my test bolt works OK. I think it'll just need a touch of fettling to fit. I think I'll use this bar, it may be scabby mystery metal, but it machines well enough. Hopefully, I've enough to do both bars...

Tomorrow's job is to mill a hexagon just about where the yellow arrow is:

...so I can use a spanner to tighten it up! I may also have to shorten the threaded section, I'm not sure how deep the hole is in the taper attachment.
Cheers!
Ade.
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Offline Darren

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Re: Project 1: Taper attachment clamp
« Reply #13 on: December 10, 2009, 03:41:22 PM »
Isn't it nice when you can turn your own threads without buying every die under the sun  :ddb:

When you come to a non-standard thread it really comes into it's own ..  :dremel:
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Offline AdeV

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Re: Project 1: Taper attachment clamp
« Reply #14 on: December 11, 2009, 05:32:19 PM »
Turning my own threads is a revelation... 6 months ago, I had absolutely no idea how to do a thread. Now, well, it works OK even if I do say so myself   :ddb:

Today was mostly spent driving up & down the M62, but I managed to grab a bit over 1/2 hour at the machines. First job was to chuck the bar in the dividing head:


I've loaded up an old, second hand, of unknown provenance 1/2" cutter to rough out the first 40 thou; I'll be taking the bar from about 0.620" to just under 0.525", or 1/4" Whitworth in old money. I could have cut a bit less out & used a BA size, but I don't have any BA spanners...

So, with the cutter aimed to remove "about enough" width, cutting commenced. I didn't use coolant & fairly tore my way through the metal. Once I was 0.040" in, I swapped to my good cutter, and prepared to take the finishing cuts:


I must have fritzed a measurement somewhere because I had to lower the cutter another 0.020" (for a total cut of 0.060", or 0.120" off the diameter) to make it fit the 0.525" spanner. Maybe when I touched off with the new cutter I was touching a burr, rather than the base metal. It didn't matter, as I was taking fine cuts & measuring after every rotation. So, after using coolant & a decent cutter, this is the result:


The spanner fits nicely:


So, a quick trip to the lathe to get rid of the burrs and to slightly round the hexagon corners later; it screws in well enough:


The paper is a 3d C-o-C showing where the clamp will live. It'll not be quite that wide (but will be nearly 4"), and will be quite a bit chunkier. Eagle eyes may note that the thread isn't screwed all the way into the taper: I will have to shorten the threaded bit by about 1/2". Which is fine, I can do that with a hacksaw. The stock isn't long enough, sadly, to cut off & make the second bar; it'll end up about 2" too short. Ubggre. I'll have to be nice to the welders to see if I can't half-inch a length of similar stock...

I've also got the block of steel I'll be cutting the clamp out of.... I think I may have gone a bit optimistic; it's about 4"x3.5"x9" and it weighs A Lot. But, it was cheap enough, and a lot of it will be cut away. Pix tomorrow.

Cheers!
Ade.
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Offline kvom

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Re: Project 1: Taper attachment clamp
« Reply #15 on: December 11, 2009, 07:44:39 PM »
It will be preferable if the clamp can slide along the bar if the tailstock interferes with the clamp.  How much space is there between the edge of the tailstock and the inner edge of the square way?

Also, is there a threaded hole on the front of the carriage?  If so, that allows , you to cut a taper at the very end of the bed where otherwise the clamp would be off the end.

Offline AdeV

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Re: Project 1: Taper attachment clamp
« Reply #16 on: December 12, 2009, 05:35:48 AM »
It will be preferable if the clamp can slide along the bar if the tailstock interferes with the clamp.  How much space is there between the edge of the tailstock and the inner edge of the square way?

The plan is to allow the clamp to move on the bars. I'd planned to have the clamp as close to the carriage as possible when the taper attachment is in it's "furthest out" position (i.e. at the start of a taper), but now I can't get 2 bars out of the one piece of stock, I'll probably leave it more or less the length it is.

To let the clamp to clear the tailstock, I can only encroach 0.100" into the slot:


However, if I'm going full length with the bar, I might be able to use the full width of the slot & just move the clamp behind the tailstock where needed.

Quote
Also, is there a threaded hole on the front of the carriage?  If so, that allows , you to cut a taper at the very end of the bed where otherwise the clamp would be off the end.

There are two holes on the front, "conveniently" much closer together than the backside edge bars. I can still go with my 2-bar plan, I just need to cut 4 grooves into the clamp area to take either the outer or inner bars. Currently, there is a stop bolted onto the front of the taper; I'll have to take that off when I clamp on the front of the unit.

Hopefully, this C-o-C makes the operation a bit clearer:

Cheers!
Ade.
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Offline kvom

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Re: Project 1: Taper attachment clamp
« Reply #17 on: December 12, 2009, 12:16:44 PM »
Quote
However, if I'm going full length with the bar, I might be able to use the full width of the slot & just move the clamp behind the tailstock where needed.
That's what I would do.   :thumbup: