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21st May 2013, 07:32 PM #1
Advice needed on this tailstock for pen turning
Can someone give me some advice with this problem please.
I am turning pens with HSS bushes as shown in the far right photo (these are streamlines). The pictures shown are from bushes and centres I use on my metal lathe to do the primary cut to the blanks. The bushes are set between head and tail centres. The pictures on the left and middle are of the tail stock centre which I bought about 2 months ago. As you can see the tail stock centre has been damaged by the bushes. It has cut into the centre.
Is this because the bushes are of a harder steel than the centres or because the angle on the bushes (60 degrees needed) is not correct?
I have the same problem with the centres on my timber lathe when using the HSS bushes.
Apart from advice on simply turning between centres and not using bushes, can anyone offer help on why this would happen.
Thanks
Greg
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21st May 2013, 09:02 PM #2Senior Member
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Looks like (IMO) the bushes are slipping on the centre causing the damage in combination with the angle being different.
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21st May 2013, 09:07 PM #3
Greg ! unless your tailstock is perfectly aligned up and down and side to side this will occur as a normal wear and tear ,although carbide is very hard it can still wear, else we never need to sharpen carbide tools
what happens if the alignment is out the centers will not be properly seated and as its spinning it will be trying to keep its alignment constantly moving ,you can't normally see this as it happens very quickly ,but the result is wear and tear as you have shown , even my live centre has wear like this . soft materials can wear harder materials ,water on rock , ships propeller shafts in rosewood or similar bearings ,the steel wears and the wood doesn't , crankshafts front seals can wear a groove from the rubber seal into the hardened crankshaft ,just a few examples , bottom line wood lathes generally are not engineered to be that accurate ,and most have no easy way to correct alignments ,even doing them between centres if the alignment is slightly out will cause wear and tear , I can't sketch what I am saying so visualise a centre drilled rod sitting between 2 centres , when in line the mating surfaces are in full contact on both ends , then move one end offset a bit ( out of alignment ) and the geometry changes ,the centres will now contact the rod in different places ,near the outer and inner sides , as it spins it keeps changing its point of contact so forming the wear you see , hope that makes sense hehe, cheers ~ JohnG'day all !Enjoy your stay !!!
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21st May 2013, 09:41 PM #4
Fully agree with what gawdelpus has said above.
Let me also clear up a couple of misconceptions in your post.
First, these bushes are made from Stainless Steel, not HSS as you stated.
Secondly, the ends that mate to the 60deg centres are drilled using standard centre drills, which have a 60 deg angle, so they mate perfectly.
If I look at what you are saying, combined with your previous thread about out of round pens, I can only come to the same conclusion that gawdelpus has come to above, there is an alignment problem on your lathe. I pointed to this in my reply to your previous thread.
Another observation, and it doesn't affect the problem you are experiencing, is that I routinely use the small centre in the Sorby set as it gives me more room to work. I have been using this centre since I purchased the Sorby set, at least 2 or years ago (will check) and it is still going strong.
Edit:
Just checked, I bought the Sorby Revolving Centre set in April 2010, in the 3 years since then that small centre has been used for every pen I have made in that time, all driving Stainless Steel No Mandrel Bushes.
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21st May 2013, 09:51 PM #5
Thanks from all. This is happening on the metal lathe so I will spend some time tomorrow to make sure it is aligned perfectly. It has been a bugger to get perfect, but trial and error Expect another post as I need more assistance in aligning it.
I will also try using the smaller centre in the set of Sorby to see how that goes. Frustrating as it seems at first, there is always a way to overcome it.
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21st May 2013, 10:50 PM #6
Please excuse me as I intrude in your conversation. The way I find best to align my two points is to place a thinnish feeler guage between the tailstock point and the headstock point bring them together gently the feeler will go in the direction of the error 360 degrees showing the up down error and side to side error clearly and simply..The beauty of using two dead centres is it brings a separation between the two points approaching the gap of one half of a pen two piece ie. I have aligned several head and tail stocks using lots of methods (courses for horses) the latest was a metal lathe tailstock I picked up at a garage sale of large size beaut throw of several inches (ideal for drilling long blanks etc).
Also I confess freely that I prefer to recess a blank brass 3/8 inch deep in my live centre another way to save mandrels and employ this method in my several machines. I will have a look now for pics.
Kind regards Peter.
3 807x480.JPGAnswer to colly wobbles 1326x743-1.JPGDSCF0001-023.JPGDSCF0001-170.JPGDSCF0001-219.jpgDSCF0001-223.JPGDSCF0002 [640x480]-001.JPGTest Photos with Digital Camera 021.jpglive centre 2 1661x852 [640x480].JPGNil Desperandum
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21st May 2013, 11:30 PM #7
Thanks for your input Peter always considerably enlightening . The main problem with Gregs Sieg c2 and also my C3 is no fine adjustment of the tailstock offset , its trial and error stuff and very frustrating as once you have it set you have to take the tailstock off the lathe and tighten the locking screw in place from underneath ,then put it back on and try again ,very frustrating indeed. I think I have a solution to both problems and will be doing something along those lines very soon Woodlathes don't seem to bother too much with offsets what you get is what you have to live with shimming is usually only to take out any excess slop between the tailstock and the bed ways . Cheers ~ John
G'day all !Enjoy your stay !!!
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22nd May 2013, 01:43 AM #8
Thanks to everyone for their replies.
Fred, I was not not being critical of the bushes as I use them all the time. I have one set for the metal lathe and another for the wood lathe. I could not understand why they were cutting into the centres but having read the replies it seems simple: my head and tail are out of alignment. Unfortunately for me the solution is not simple as I will have to try and align them properly. When I bought the metal lathe John (Gawdelpus) came up and spent a couple of hours trying to align it properly. It seems the manufacturers only get it close and not precise.
I bought a new mandrel at the WW Show and put it on the wood lathe because my previous mandrel was bent. I used an adjustable mandrel and also one of the tail stock hollow mandrel holders and guess what - still not straight. I will spend some time on it tomorrow to see if I can get it right. It would be nice to work out a way to get the head and tail stock precise. This would overcome my problems. I won't use the smaller 60 degree until I do otherwise it will damage it too.
Peter, I will try your method as best as I can follow it with the feeler gauges and perhaps shims.
Will let you know how it goes.
Greg
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23rd May 2013, 10:45 AM #9
Greg,
Behind the 8 ball for time now but i have drilled 4 holes in the base of my tail stocks with brass screws tapped into the holes recessed locknut to centre the tail stock and shaved on one tail stock base to bring it down a touch. So effectively the screws can be replaced when necessary from future wear. Headstock mounts have some latitude to gain adjustment. But you cant get kittens from a cat named george.
Have success Peter. PS. Craft Supplies have the very best mandrel saver IMHO. I will take pics of it for you and send later in this week it consists of a 2 morse taper shaft with a neat fit through a bearing of quality I will explain my experiences with this unit now happy to recommend it.
Kind regards Peter.Nil Desperandum
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23rd May 2013, 01:46 PM #10
Greg, Send me a pm with your E Mail addy so I can send pics soon.
Thanks Peter.Nil Desperandum
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23rd May 2013, 07:31 PM #11
Peter
PM sent. I would appreciate the photographs. Thank you for your offer.
It is very frustrating trying to get both lathes set up properly, particularly given I have no technical experience with lathes and certainly no experience in turning metal or making bits and pieces that I might need. However, I will persevere and try to learn more so I can get things done myself - maybe
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24th May 2013, 09:18 PM #12
Thanks very much Peter for the photos. I have been poring over them today and trying to work out how to get things fixed up. Thanks also to John who sent me an idea that might just work. I went thought the manual to try and work out how to apply it and it is starting to become a reality in my mind
I will have a longer look at my lathes in the morning to see how I can apply the ideas - should only take me 8 hours
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