pillar drill column

I need a new length of steel for my startrite pillar drill column 1.5 metres long would be fine

it needs to be 2 3/4 " diameter

any suggestions on where to source such material and will it need grinding to size or will bright drawn be ok wall thickness is 4mm or thereabouts

Ian

Hi Ian

M Machine Metals list a 2.75"dia x 1/4" wall steel tube here ...............

SIT DOWN NOW......

AT £27 PER 300mm !!!!

Good luck!

Norman

Thanks for that they only want £30 for solid steel (per 12"

would bright drawn be ok? what would the tolerance be on diameter?

any body got any idea where to get some cheaper ( scrap) from?

You could try searching "seemless hydraulic tube" and see if you can find someone near you.

Dave

Schaffold tube? and bushes?

Ian,

Just out of interest - what happened to the orginal. If it is just rust? You might be surprised how well you can recover it. I had to do a lot of work to retrieve my drilling machine and lathe cabinet.

PhilH

Ian

Have you tried these guys? http://www.machinespares.net/document-library/select-machine-type.php?brand_id=1 They do Startrite spares.

Although they have no 'to buy' on the column they may be able to source one for you. Probably not cheap either, though....

I bought the machine and someone had modified it to a large throat by chopping the column and extending the head out by 24" or so

Ive welded it back together but would really like a longer column a s the startrite has a tall base casting and the head has a 2 speed epicyclic gearbox on it as well so room under the chuck is limited

I'll have to trawl the scrap yards round sheffield for a length...the reason or my post was what sort of steel finish do I need to allow the table to move and clamp well......is bright drawn solid OK or is seamless tube OK or does every type need to be ground to 2 3/4 "

got to agree with this

find some scaffolders iin the area and give them a couple of quid for a length appropriate to your needs

then bush it up to your hearts content
jobs a good'un

most scaffold tubes are 47mm and galvonised

Edited By Ziggar on 16/01/2013 18:55:33

There will be a HUGE difference in stiffness between scaffold tube and 2 3/4" steel tube (especially if you get ally scaffold tube). They didn't use a column of that diameter originally just for fun.

Good point not least with 70 mm solid vs 47 mm od tube...

But would it be stiff ENOUGH?...

while we think about that. What would be the consequence of a longer pillar (say double) of the original section be ,to the machines STIFFNESS?

Try a supplier of hydraulic ram material or maybe look for a scrap one, it is chrome plated and very accurate for size. Don't worry about cutting through the chrome you can nick it with a grinder then it will cut with a saw.

Hello Ian

Bright drawn bar will be fine if you can get it at the right price. It is formed straight and round but the surface finish can vary between batches. It is also usually a few thou or more undersize, but this can also vary.

We use bright drawn bar at work and i have once had to use undersize 70 mm bar where 2 3/4 was needed as it was a better fit than the undersize 2 3/4 bar we had. If you wish i can ask them to give me a price for the length you want, i don't live very far from Sheffield.

Seam welded steel tube isn't always formed very round, at least not for a good reliable fit in the bore of your drill head and table casting, with or without a bush.

Scaffold tube to me just seems too rough and flimsy as a replacement. You might find the table and head being pushed away from each other as the column flexes when using the larger drills that your backgeared drill head can manage. If you are not careful you might just end up with a rubbish drill.

I have an Elliot Progress 2G backgeared pillar drill that uses a solid ground steel column of similar diameter to yours, as standard, sat on a tall square cast iron column. I have often thought about using bright drawn bar of the same overall length so that the table can be lowered further to gain more room under the head.

 I will also have a look and see if we have an old hydraulic ram, as JohnF suggests, lying about.

All the best

Edited By Lathejack on 17/01/2013 01:49:15

Jason,

The deflection of a solid round beam fixed at one end and loaded at the other is proportional to L^3, so doubling its length will increase the deflection by a factor of 8.

The formula is Y = 64*F*L^3/(3*pi*D^4) where Y is deflection, F is applied force, L is length and D is diameter.

For a hollow round beam, replace D^4 with (D^4 - d^4) where D is outside diameter and d is inside diameter.

The formula is different for other cross sections; a Google search should lead to the answer for anyone interested.

Incidentally, this shows why (a) stub length drills are so much stiffer than standard length ones, and (b) it's always worth swapping your small boring tool for one of even slightly greater diameter as soon as it will fit the hole.

David

Edited By David Littlewood on 17/01/2013 01:46:09

If you get tube I think you should get at least twice as thick as the 4 mm you suggest, particulary if you are going to extend the length, you want ridgidity, and minimum vibration. I,d be looking for old hydraulic cylinder, or ram of suitable size, with any luck the ram might be straight, If its over size, you might need to borrow a bigger lathe. Ian S C

Thanks for all your replies

I would not consider using scaffold tube far too flimsy and rough surface finish to take the table and be able to move it

I was only wanting an increase in length of about 6-12 inches over what i have available now

Lathejack if you do find an old ram I look forward to hearing from you

Ian

If you do find a piece of tube with the correct outside dia. but thin wall ,it would be worth filling it with concrete, maybe with a wire or two for added strength.

Alex Weiss in ME 07 Apr 1995 page 434 extended a NuTool DIY13 by 100mm/4inch using a piece of scaffold tube.

I have used his idea on a NuTool CH10 but had to use a solid extension piece due to the difference in column size.

Regards,

Peter G. Shaw

I have extended my pillar drill by 150 mm, see **LINK**

Mike