Cutting nylon bar

[BillJ]

I need to cut 12mm dia nylon bar into pieces approx. 18mm long. I say "approximately" because I can't remember the exact measurement off the top of my head but the length actually needs to be precise.

At the moment I am doing this on the bandsaw but that leaves a rough cut and a lot of swarf to clean up. I've tried using a hand-held MDPE pipe cutter and this would cut cleanly two-thirds of the way before the piece snapped off so it looks promising but not quite there.

I would appreciate any suggestions for doing this cheaply and fairly quickly (I cut quite a few for each batch) but also cleanly. The bandsaw is fast but the cleanup takes time. I wondered about something using heat but I don't want to invest too much in tooling as it would take quite a while to recoup the cost.

 

[Engineer1964]

I always cut mine when required on a lathe if you havn't got one then ask at a local engineering company, they may get the guy to do it for a drink for you

 

[scott0031]

What you need really depends on what you mean by 'precise' and the quantity you need. If you have been doing this on a band saw and it does the job then the precise' you need isn't very precise.

A chop saw/ cold saw could be used and give a pretty good finish, it will still leave some form or burr on the OD which is always a pain to clean up on any nylon let alone round, which is the worst.

As Engineer mentioned a lathe is a better option, although a center lathe is relatively slow to the next option.


An automatic lathe is the best options which is the most cost effective way per part. This is where the quantity you need comes in to to play and you would need to be prepared to buy a few and stick them on the shelf for the next order. You would get the bar machined to length. +- .025 mm comfortably and chamfered on the OD, A small pip may be present which will have to be knifed off. You get a part ready to go and its one shot machining and cycle per part is about 10 sec approx. The hard bit will be finding someone with an automatic as they are not that common these days.

Some pics of automatically turned parts both stainless. Long part threaded the full length of the shoulder. Note: This is not CNC

kind regards,


Scott

 

[BillJ]

Thanks, guys.
By "precise", I don't actually mean very precise, just that they need to be the specified length within about 0.5mm or so.
I do have a "toy" lathe and I make the steel bits on that. I found it a bit of a faff parting the nylon bar on it, though.

A "pip" in the middle doesn't matter as I drill the centre anyway.

I make batches of 30-50 at a time. The problem is largely down to cosmetics - once the customer fits the part it is not visible but I don't want it to arrive at the customer looking home-made (despite the fact that, strictly-speaking, it is).

 

[bigbadbugga]

Could you not just keep cutting them the way you do now but a little long, and face them off in the lathe?

 

[guiness]

in work we finish nylon on the linisher for a smooth finish

 

[Pete.]

I'd make a 'bar shear' by drilling a plate with a hole the size of the bar and then shear across the face of that hole. The good fit should prevent it distorting and snapping.

 

[BillJ]

The shear sounds interesting and wouldn't be hard to make. I might give that a go. Thanks!

An automatic lathe would be a great toy and would make it so easy to do the other parts. I must start saving for one...

 

[tigler]

The quantity is the problem with subbing out, any auto machine would do 50 in seconds so the major cost becomes setup and order processing, which menas you get into minimum charges.
Which eliminates what I would have suggested, water jet cutting.