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ams
12-01-2014, 11:52 AM
Hi

I have 5 parts I need turned. There are 2 cylinders which are pprox. 440mm long and 25mm in diameter. The other 3 parts are approx. 450mm long and 6.7mm diameter. There is very important detailing and threading to be done on 2 of the parts.

Please let me know if you could take on the job. I will provide engineering drawings and 3D CAD files. I could also supply the steel round bar if neccessary.

Thanks

Jonathan
12-01-2014, 04:54 PM
'450mm long and 6.7mm diameter'

That one is going to be challenging if the diameter needs to be remotely accurate, as the length to diameter ratio is very high.

irving2008
12-01-2014, 09:53 PM
Will definitely need a good quality toolholder mounted travelling steady to get any degree of diametrical accuracy...

Lee Roberts
12-01-2014, 10:30 PM
The other 3 parts are approx. 450mm long and 6.7mm diameter.

Could you not go to 8mm or down to 6mm for these parts as per the other posts above this one?

.Me

EddyCurrent
12-01-2014, 10:51 PM
1/4" might also be an alternative if you're thinking about using standard stock

Lee Roberts
12-01-2014, 10:57 PM
1/4" might also be an alternative if you're thinking about using standard stock

Doh of course!

m_c
12-01-2014, 11:29 PM
Swiss/sliding head lathe, or a roller box would take care of the 6.7mm.

ams
13-01-2014, 12:17 AM
I cant change any dimensions unfortunately because these parts fit into the entire assembly, I'm sure there's room for error but it would be small and difficult for me to estimate. Anyone willing to take a crack at this?

irving2008
13-01-2014, 06:48 AM
I cant change any dimensions unfortunately because these parts fit into the entire assembly, I'm sure there's room for error but it would be small and difficult for me to estimate. Anyone willing to take a crack at this?

You're going to need someone with a lathe & travelling steady (or sliding head) that can turn 20"+ between centres. Can't think of anyone here, with the exception of maybe JohnS, that has a big enough lathe. What's the tolerance on the 6.7mm?


Also, the 'cylinders' - do they have an internal bore? Or are they solid?

I know someone who has access to a cylindrical grinder, rather than a lathe, that might be able to do the long thin parts as a 'homer'.

ams
14-01-2014, 11:38 AM
You're going to need someone with a lathe & travelling steady (or sliding head) that can turn 20"+ between centres. Can't think of anyone here, with the exception of maybe JohnS, that has a big enough lathe. What's the tolerance on the 6.7mm?


Also, the 'cylinders' - do they have an internal bore? Or are they solid?

I know someone who has access to a cylindrical grinder, rather than a lathe, that might be able to do the long thin parts as a 'homer'.

Hi

Yes the 2 cylinders have an internal bore, the other 3 smaller parts are solid. If there's someone you think would be able to take this on please message me and I can send across drawings and 3d models.

Thanks

irving2008
14-01-2014, 12:35 PM
how long is internal bore? full length?

ams
14-01-2014, 12:41 PM
Yes full length

irving2008
14-01-2014, 03:20 PM
That's going to be near impossible to make unless the tolerance on the bore is very loose so it can be made from a bit of tube. to bore out a 25mm OD cylinder 440mm deep is going to need some very specialist tooling. I hope you have deep pockets...

m_c
14-01-2014, 06:50 PM
As irving says, machining that depth and that narrow will be abit challenging. You may want to look to see if there's any hydraulic cylinder tubing available in a suitable size.

Robin Hewitt
14-01-2014, 07:57 PM
I had 3 foot of 1.5" diameter steel rod drilled through and honed to 0.5" a couple of years ago.

I forget who did it but it wasn't expensive, I think they used a gun drill, I used Google :beer:

AdCNC
14-01-2014, 08:53 PM
Swiss/sliding head lathe, or a roller box would take care of the 6.7mm.


TBH i think a Swiss/sliding head is the only way to go for this sort of job if accuracy is important.

irving2008
14-01-2014, 11:24 PM
I had 3 foot of 1.5" diameter steel rod drilled through and honed to 0.5" a couple of years ago.

I forget who did it but it wasn't expensive, I think they used a gun drill, I used Google :beer:
Hi Robin, yes it can be done, and I'd not thought of a gun drill but it needs specialist equipment. A gun drill and a lathe with a 1m+ long bed to use it isn't something most people here have access to!

Premier Deep Hole Drilling Limited - The Deep Hole Drilling Process (http://www.premier-drilling.co.uk/process.htm)

corkcnc
14-01-2014, 11:27 PM
Sliding head is all well and good for the OD but I'd agree with RH that a gun drill is needed for the ID for any bit of accuracy. If you started off with a tube with the ID already close enough to the required finished dims then the bore of the tube might keep you in line (with a new drill - symmetrical point angle and both lips even) but not for tight tolerances. You would need a long travel to accomodate the long drill or a gun drill at starting point and the material held either with the rear in the chuck and front on a fixed steady or else the front of the job in the chuck and the rear in a custom collet at the "back" of the chuck, i.e. left side of the machine.
It's quite specialised but for those with the correct tooling it shouldn't be overly complicated. Cylindrical grinding as mentioned previously would be the most cost effective method of achieving the final ODs on the smaller shafts.
Best of luck with it.
Noel.

(Edit: Looks like Irving said what I was trying to say about 2 minutes ago :) )