Back on the vibration trail

[docusk]

<TABLE class=forumline cellSpacing=1 cellPadding=3 width="100%" border=0><TBODY><TR><TD class=row2 vAlign=top width="100%" height=28><TABLE cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR><TD colSpan=2>My main problem seems to be of my own making.
Some of you may recall that I have re-tooled recently and bought a Record DML 36 with bowl turning attachment. I had loads of good advice from you guys and gals and for much of my work, it's fine but I still get some vibration despite following the excellent advice from the record Power website and the Oz based woodworkers forum!
here's what I'm wondering.
The bench is made out of 3" X 7" X 42" planks from B & Q, (our major DIY shop chains - www.diy.com (http://www.diy.com) finds them) laid edge to edge, 3 deep. The legs are 4" X 2" and are set in three rows of 3 deep from the right hand end, rag bolted into a solid concrete floor via purpose made mild steel brackets, whilst the left hand end and the rear side are each carried on a 2" X 2" wooden bearer attached with large coach screws to a breeze block wall.
I have built a shelf underneath which carries two bags of sand about 14 Lb each to al least dampen the vibration a bit. (that was advice from here chaps, worked like a charm for bowls and clock boards)
What I'm wondering is that I built the bench fairly high, over 3' from the ground because I'm disabled and wanted to be able to sit whilst turning. That has never worked so I'm now looking at one of two solutions.
First that the bench might be too high and should come down to about 2' 6" or so and the other solutiion is to buy the purpose built frame for the DML 36 and use the bench elsewhere. I don't need it so high I find because I can now stand for quite long periods I find, must be that English weather.
At present, I can't turn spindles to a fine diameter unless they are less than 12" and even then, I have another bag of sand hanging over the rods to the right of the tailstock.
I have asked about the strong angle iron frame made for the CL line of lathes but Record tell me it won't do, only the £40 tubular model will work with my lathe. The Record Techies say it will solve my problem but I'd as soon try and salvage what I have which is why I'm asking the experts on this band.
Any thoughts on the foregoing most welcome.

[I was getting better results with my old lathe which is an old fabricated, square box bed machine that cost about £75 new some 20 years ago! ]

docusk
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[orraloon]

Docusk,
I think that the 4''x2'' legs are the problem. They seem a bit light to me You can beef them up by gluing and screwing another 4x2 to each leg. Another way to stiffen the bench is to box in the back and sides with ply or some other sheet. There is a down side to boxing in as the bench can then become a bit of a sound box but adding weight will change the effect and dampen things down. I think wood is better at absorbing the vibrations than steel legs but it has to be chunky and solid. My bench was built for a record dlx24 but is still ok with a larger lathe on it. Just for information I used the basic bench plan from Keith Rowley's Foundation Course.

Regards
John

[hughie]

Docusk,

I think your right your legs are letting you down. I use a different method of building a lathe base. aka Bruce Leadbetter of Leady lathes

Basically I make the legs hollow out of 3/4plywood. With a cavity about 3" wide, the legs are splayed out like short triangles...sori no pics.
Which give width to leg and stability. Then I fill them with sand, 14lbs nah more like 100lbs per leg.

Then I use 'Stu in Tokyo' suggestion of making four feet laminated out of 1/2 plywood, cork and rubber. Plywood then cork, plywood again then rubber and plywood for the last piece. Size is about 3"x4" and the idea is that they absorb any vibration from the turning. With the sand filled legs generally theres not allot. Except roughing out out of balance large bowl blanks.

So far so good although I suspect the cork will give and break down, shoulda gone with rubber all the way.

The only hassle is, if your a compulsive workshop re-organiser the lathe wont move with out some serious effort :U

[docusk]

Thanks for the advice, you both seem to have come up with similar solutions! I can see what the point is now. I shall start on fabricating a new bench after Christmas. Thanks again.
Always rely on you guys in the Antipodes!
Funny, my son-in-law (the engineer) says, in their workshop they used to build a sort of cabinet att the bottom of the lathes and fill them with concrete.

docusk

Have a good one all of you wonderful people. Wish I was there, I can't be arsed with this cold weather. Keeps me out of the workshop till it's all warmed up.

(Thinks* The wife used to say something like that?)

[killerbeast]

sound stable ... anybody have experience with permanent wheels ?? i have some heavy duty ones from a roadie job last summer.. i think they are 1000 og 1500 kg. a pice.....

but i worrie about havind four "small" point that the lathe stand on...

[docusk]

Oraloon.
Any chance of you giving me the approx dimensions of the legs. I have downloaded the photos and now would like to make the legs whilst I'm doing the shop re-organisation.
A private message might be the way?
docusk

[orraloon]

PM sent.

[docusk]

Orraloon.
I know it's going back a long way but, as you see I'm a bit long in the tooth and had a bit of a bad year for most of 2007 and all was left unfinished. :doh:
I bought some of the wood but can't find any trace of the PM you sent with the detailed dimensions. Could you bear to do it again. I'm sure I have the pictures somewhere.
Whatever, I'm finished with the medical monsters (I hope) and seem fully recovered - with any luck - so want to get doing some decent turning again.
I'm about to make a start on clearing the cobwebs from the w/shop, some of 'em are as much as 18 months old!
Hope you get this.
docusk

:2tsup:

[oldiephred]

I seem to have missed the earlier version of this problem with vibration so may I ask a couple of questions?
1/ what is the source of the vibraton and what problems does it present?
2/ If you are turning heavy, out of balance pieces at a high speed do you think you can eliminate the vibration?
3/ doesn't the vibration subside as the piece becomes symetrical?
Something must "absorb" the imbalance shock and if not the stand, then the lathe bearings and other parts will eventually suffer.
Anyway good luck

[Chipman]

Docust, it is strange that you are not getting the vibration with bowl blanks but getting it with fine spindles:doh:

A bowl blank is much more massive and more likely to cause vibration from being out of round. The best way to control that sort of vibration is to use a slower speed until you have it rounded up.

Now for the spindles, especially if fine or small diameter. These of themselves can never cause that kind of vibration! (I have a woodfast midi lathe that just sits (no bolts) on an ordinary cupboard with a thick piece of chipboard and it never vibrates or bounces around doing that sort of work. I am suspecting that your tailstock is not lining up with you head stock...

Move the tail stock right up to the head stock and check that the point of the live centre lines up with the point of the drive dog. If it is not lined up, it will cause your vibration problem. If the vibration is not there with now spindle mounted but is there when mounted and spinning (without any work being done on it).. it is likely to be an alignment problem.

If it is not that... check that you are not applying too much pressure on your spindle work by winding the tail stock in too far. It causes the spindle to go out of line and whip around causing vibration. (On an old lathe, I have seen play in the live centre/tailstock allow the end to go out of line and end up with vibration and oval turning but should not be a problem with a new lathe) Try backing off a little pressure and see what hapens...

Another thing is the turning technique...especially for thin spindles. If you are cutting below the centre line it causes the spindle to rise up over the tool and it flexes/vibrates when it jumps back off. Tools need to be very sharp and the smaller the spindle the faster you should turn it. The other thing is a bit scary at first, but when you see pro's turning lace bobbins and the like, they always support the spindle with their other hand as it turns! If your spindles are bigger than that, consider using a steady to support your work while you turn. If the vibration is only there while you are working, technique and tool sharpness is the likely cause...

Give it a try, I don't think the problem is entirely in the legs.....
Alternatively, see if you can get another turner to come around and check your lathe out.

Cheers,

Chipman:)

[docusk]

Oldiephred.
I expect you've read the rest of the thread by now. The bowl blank had an "Oyster" on one side but once I had sorted that - reducing speed and puting lots of weight on the frame of the lathe bench - I finished it and it is extremely beautiful now. The problem of the vibration remains and Orraloon sent me details of measurement of his bench (photos above)
However, illness intervened and I was out of things for months. Now I'm rarin' to go so I need to get the bench sorted.
Main thing, I'm sure, is it's too high at about 3 feet to bench level, then add the lathe and it's up above the clouds.
That's where I am now. I think I may have found the drawings with dimensions in the computer so maybe make a start next week. If they are the wrong ones, I'm back to square one!
docusk

[orraloon]

Docusk,
I will have a look at the sent emails just in case it is still there. I seem to remember you said you had got a copy of Keith Rowlry's book so all the detail for a bench will be in there. I differed from his plan in that I glued 2 sheets of chipboard flooring to make a 38mm (1 1/2") thick top.
Regards
John

[docusk]

Orraloon,
Yes OK. It was a PM you sent me. I'll pore through Rowly's book and PC that but remember your tip about the top.
Thanks for reply.

docusk