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Convex buffer face

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paul rushmer21/09/2018 12:40:18
79 forum posts
11 photos

I hand tool mine using a file ground smooth on the end and sharpened like a wide parting tool, the tool rest being a round rod held in the tool post. Check the profile by eye and feel polish with emery to finish. This method is quick simple and easy. Just be carful.

Paul

KWIL21/09/2018 15:14:31
3234 forum posts
63 photos

Pointy radius rod and the DAG Brown approach produce identical items so there is no guess work to make them look OK.

Ron Laden21/09/2018 15:25:19
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1921 forum posts
367 photos
Posted by Mick B1 on 20/09/2018 21:46:16:

I've never actually done this, but an experienced turner showed me a method using a pointy rod the length of the required radius located in deep dot-punches below spindle centreline on headstock and crossslide chuckside face.

You use the saddle handwheel to keep the radius rod in contact both ends, whilst traversing a tool across the workface. The saddle moves away from the chuck to generate the radius. You arrange the tool so that it reaches centre when the radius rod's parallel to the bedways.

It's fiddly, but it's simple, accurate and I've seen it work.

Thanks for this idea Mick, I gave it a try on a test piece and it works really well and is easy to do. The only problem I have is the four blanks which I have for the buffers are 70mm long and the radius needs to be around 200mm. A 200mm guide rod keeps the cross slide too far way from the workpiece even with the top slide fully wound in, I,m using a mini-lathe by the way. The blanks need to be around 125 mm long and then it will work, however all is not lost.

A machinist friend supplied me with the 70mm blanks (FOC) which was very good of him, I dont know the grade of aluminium but it is the hardest I have come across. The 3.2mm parting tool I have works really well as a groove tool (well on good machining aluminium at least) but it doesnt like the material my friend supplied. So I need to get a softer grade and longer blanks and then I think it will be fine.

Thanks again

Ron

 

Edited By Ron Laden on 21/09/2018 15:26:45

Edited By Ron Laden on 21/09/2018 15:28:14

 

Edited By Ron Laden on 21/09/2018 15:53:52

Ron Laden21/09/2018 15:29:56
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1921 forum posts
367 photos

Sorry, dont know why my above reply is in miniature, cant seem to change it..?

Ron

Michael Gilligan21/09/2018 15:35:15
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15712 forum posts
687 photos
Posted by Ron Laden on 21/09/2018 15:29:56:

Sorry, dont know why my above reply is in miniature, cant seem to change it..?

Ron

.

Ron,

It's because you started typing in Mick's edited text ... The formatting was carried over from that.

MichaelG.

Ron Laden21/09/2018 15:39:08
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1921 forum posts
367 photos

Thanks Michael, I didnt realise that.

Ron

Ron Laden22/09/2018 11:56:23
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1921 forum posts
367 photos

Sorry for the not too good a picture of a test piece and the guide rod using the method that Mick put forward, it is really easy to do and works a treat...thanks Mick. Good thing is of course, you get repeatable results when producing more than one item. I just have to get some better material before I machine the buffer set, the stuff I have been given is awful, dont know what it is but terrible to machine.

dsc06101.jpg

Ron Laden27/09/2018 08:36:40
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1921 forum posts
367 photos

Well, I managed to produce the first of the 4 buffers (non sprung) using the guide rod method, I think it turned out ok. The buffer is tapped M6 for mounting to the chassis plate, just need to go over it with some wet or dry to remove some scratches from the base.

It took me over two and a half hours to produce from a 35mm dia blank, slow I know, but I guess a lot of that is down to inexperience plus I still dont tend to push the mini-lathe. I know its alu but I didnt take any cut deeper than 10 thou, the balance of 3 should be quicker though but I,m not in any hurry.

Ron

dsc06103.jpg

Edited By Ron Laden on 27/09/2018 08:39:43

Martin Kyte27/09/2018 12:47:42
avatar
1842 forum posts
33 photos
Posted by Ron Laden on 21/09/2018 15:25:19:
Posted by Mick B1 on 20/09/2018 21:46:16:

I've never actually done this, but an experienced turner showed me a method using a pointy rod the length of the required radius located in deep dot-punches below spindle centreline on headstock and crossslide chuckside face.

You use the saddle handwheel to keep the radius rod in contact both ends, whilst traversing a tool across the workface. The saddle moves away from the chuck to generate the radius. You arrange the tool so that it reaches centre when the radius rod's parallel to the bedways.

It's fiddly, but it's simple, accurate and I've seen it work.

Thanks for this idea Mick, I gave it a try on a test piece and it works really well and is easy to do. The only problem I have is the four blanks which I have for the buffers are 70mm long and the radius needs to be around 200mm. A 200mm guide rod keeps the cross slide too far way from the workpiece even with the top slide fully wound in, I,m using a mini-lathe by the way. The blanks need to be around 125 mm long and then it will work, however all is not lost.

A machinist friend supplied me with the 70mm blanks (FOC) which was very good of him, I dont know the grade of aluminium but it is the hardest I have come across. The 3.2mm parting tool I have works really well as a groove tool (well on good machining aluminium at least) but it doesnt like the material my friend supplied. So I need to get a softer grade and longer blanks and then I think it will be fine.

Thanks again

Ron

Edited By Ron Laden on 21/09/2018 15:26:45

Edited By Ron Laden on 21/09/2018 15:28:14

Edited By Ron Laden on 21/09/2018 15:53:52

the point where the rod touches the cross slide doesn't need to be on the front face. A suitable piece of angle or something extending to the tailstock side at a convenient position would serve just as well.

regards Martin

Ron Laden27/09/2018 13:16:02
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1921 forum posts
367 photos

Thanks for that tip Martin, I never thought of that but I can see how it would work.

Ron

Jeff Dayman27/09/2018 14:34:31
1818 forum posts
45 photos

Your buffer looks great Ron, nice job!

Neil Wyatt27/09/2018 15:29:31
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Moderator
17893 forum posts
706 photos
77 articles

Nice job Ron.

The maximum 10-thou cut in the manual is a bad joke. Don't be afraid of 1mm in steel or 2mm in aluminium alloy as long as the rpm isn't too low.

Let's face it, when parting you are going to be taking cuts typically between 1.5 and 3mm without overloading the machine.

Neil

Ron Laden27/09/2018 17:14:44
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1921 forum posts
367 photos

Thanks Jeff

Thanks Neil, point taken, when I make the other three I will get a bit braver with the cuts. The buffer ram is 14mm dia and the ram body 19mm from a 35mm dia blank so you can see why it took me so long.

I did have one scary moment though, whilst I was turning the front face radius the cross slide suddenly kicked forward about 4mm, fortunately no damage was done. When I checked, the cross slide had gone from its normal 0.1-0.2mm backlash to 4mm. The two cap heads that hold the leadscrew nut had worked loose without me realising. I set it up again using the method you describe in your mini-lathe book and all is now well.

Ron

not done it yet27/09/2018 19:06:43
4645 forum posts
16 photos

Who really cares if it took that long? Better to make slow progress rather than c*ck it up. You are not trying to make a living at this! Experience and confidence will follow. The final outcome looks very good - and that is what matters.

You will soon find that ‘roughing out’ material with a lesser surface finish takes a lot less time than doing it like finishing cuts all the way through.

Lainchy29/05/2020 12:51:02
avatar
244 forum posts
95 photos

I love this forum for tips! Found this under a search. I have to do the same on my Juliet, albeit that it doesn't quote a radius. Looking forward to having a go though now

Thanks ME

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