Thread cutting in chinese ballscrew
Hi there
Does anyone know if it's possible to manually cut a M10x1.5 thread into Chinese C7 1605 ballscrew with a die?
I haven't tried yet but it looks like super hard steel...
Otherwise I'm going to need to find a friendly machinist here in froggy land... rare indeed I should imagine in these mountains!
Ta
Jo
Re: Thread cutting in chinese ballscrew
Typically, the outside of these ballscrews is very hard, but the hardness is just a skin and the core is relatively soft. If you are talking about putting a thread on a plain end of a ready-machined ballscrew, then that would probably be OK (tough-ish steel but machinable) but I wonder why you would do this? Usually, this is where the pulley goes and you want that to be a close sliding fit on the ballscrew. A thread is most definitely not a good surface to bear on, and a thread cut by a die is very, very unlikely to be square to the shaft. OK for simple nut-and-bolt type work, but not if you are looking for accuracy/parallelism/concentricity, etc.
Some people talk about being able to turn the end of ballscrews with carbide tools and get under the hard skin; others soften the end first before machining. However, that is to turn the end down to the nominal 10mm or whatever, and if you are doing that then you would also be in a position to screwcut the thread on a lathe. A machine that justifies ballscrews justifies decent machining of those ballscrews or you are just throwing away accuracy.
But maybe you have something else in mind? Not sure what the real requirement is here.
Re: Thread cutting in chinese ballscrew
Good luck with that. They can be done on a lathe. If you put a wet rag near the end and anneal it you just might do it. I am not sure without checking I thought they were M12x1
Re: Thread cutting in chinese ballscrew
They can be screwcut with tipped tooling but I wouldn't fancy my chances with a die.
Re: Thread cutting in chinese ballscrew
Thanks for the quick response...
I am doing a CNC conversion on a Warco WM16 and I'm following Hoss's design (more or less) I've had the screws machined in China but they neglected to put a thread for the Ballscrew retaining nuts on the Y axis... with this plan the 1605 screw is reduced to 10mm for bearings and then tapped at M10 x1.5 and finally reduced to take the motor coupler...
Hadn't even considered squareness to shaft...
Re: Thread cutting in chinese ballscrew
Is squareness going to be a massive issue in this case the nuts only serve to retain the ballscrew in the fixed bearing holder?
Ta
Re: Thread cutting in chinese ballscrew
Quote:
Originally Posted by
noyloj
the nuts only serve to retain the ballscrew in the fixed bearing holder?
Only?? Its what gives the ballscrew its rigidity and stops backlash etc. etc....needs to be square and true to put equal pressure all round on the bearing race.
Sent from my HUAWEI VNS-L31 using Tapatalk
Re: Thread cutting in chinese ballscrew
Quote:
Originally Posted by
noyloj
Is squareness going to be a massive issue in this case the nuts only serve to retain the ballscrew in the fixed bearing holder?
Ta
As the man says, squareness is absolutely important. The bearings typically come with a retaining nut with an accurately (one hopes...) machined face specifically for this purpose. From memory, the nuts on mine didn't look like standard M10 - aren't they a much finer thread (like 1mm pitch, not 1.5?). Might be interesting to find a die of that size.
Re: Thread cutting in chinese ballscrew
Quote:
Originally Posted by
Neale
As the man says, squareness is absolutely important. The bearings typically come with a retaining nut with an accurately (one hopes...) machined face specifically for this purpose. From memory, the nuts on mine didn't look like standard M10 - aren't they a much finer thread (like 1mm pitch, not 1.5?). Might be interesting to find a die of that size.
Ok, though Hoss's plans don't specify any machining of the nuts in so far as I can see. I think he must rely on single point of contact being adequate to prevent axial travel since the bearings are held captive radially by the housing, but point taken the squarer the better!
Neil I agree... 1mm pitch would be much better as less material would be removed meaning easier cutting hopefully and I could buy lock/jam nuts specifically, good idea!
Perhaps if I set up my rotary table in the vertical position I could work out some way to hold the die somehow with the tailstock and allow it to slide forward as I turn the ballscrew in the chuck? Crazy or totally crazy?
Re: Thread cutting in chinese ballscrew
Quote:
Originally Posted by
noyloj
Ok, though Hoss's plans don't specify any machining of the nuts in so far as I can see. I think he must rely on single point of contact being adequate to prevent axial travel since the bearings are held captive radially by the housing, but point taken the squarer the better!
Neil I agree... 1mm pitch would be much better as less material would be removed meaning easier cutting hopefully and I could buy lock/jam nuts specifically, good idea!
Perhaps if I set up my rotary table in the vertical position I could work out some way to hold the die somehow with the tailstock and allow it to slide forward as I turn the ballscrew in the chuck? Crazy or totally crazy?
So if you are following the usual dimensions you will find the a M10x1.5 does not pass over the 8mm section. We typically use M10x1.0 as it also allows you to get a finer adjustment on the locking nut.
In answer to your original question, if you have rolled screws, then yes, you can use a die. I have done this with a M10x1.0 and as long as you are square on, you will be fine. You may need to use more lube than usual here.