This forum is an incredibly resource for online help and advice on almost any subject. OK some threads wander a bit but often the wanderings themselves are really informative and I personally have learned a lot here.

Occasionally members here do offer actual physical help to a fellow member when they the people concerned are located near enough to each other and when one person has some facility or skill they can impart of offer, like a larger lathe or a spark eroder for example.

I was wondering whether there should be a forum section for members to ask for assistance (free/paid, or whatever) so make the task of accomplishing difficult tasks possible.

Obviously I have an ulterior motive! I need to machine an O ring groove in a rectangular shape in some Delrin. Doing this without a rotary table is possible (but I don't have one) so what I really need is a small CNC milling job doing, I there anybody in the Cheshire area who I could discuss this with?

Regardless of my requirement, I still think there might be some mileage in the idea.

Ian P

Les, you are right about people not giving their location but I doubt its because that cannot be bothered, more about not wanting to give personal details (although a county or a town is hardly personal!). Sometimes the poster might be asking about where to buy something, its pretty pointless anyone replying without even knowing which country the question came from. (Rant over)

Thank you for your offer. I did state correctly that I don't have a rotary table in the accepted sense. I do have a thick aluminium disk mounted on on old automotive front wheel hub that I can rotate manually and with lost of jigging around can index or rig up end stop positions. The groove I want to do is about 3mm wide and 3mm deep in the endface of a 12mm wall thickness rectangular tube which is about 150×180.

To correctly get an accurate transition from the straight sides to the radiused corners will require an awful lot of setting up whatever the rotary table is like, and I want to cut two of these grooves.

Without CNC what is really needed is an X-Y table mounted on a rotary table, not that I have ever seen one setup like that. Even then the potential to turn one handwheel the wrong way once makes getting it right first time very unlikely for me!

I did get a PM from another (non local) CNC equipped forum member which I am investigating.

Ian P

I see what you mean.

I have not watched any of the Youtube videos but I imagine that setting one up would be good fun. Bring on CNC!

Ian P

Thanks to all who offered advice and help with this problem. More than one person has offered to cut the groove for free which I am really grateful for. One member did not reply here, but PM'd me and I have actually posted the lump of plastic to him.

Russ, I have PM'd you but thank you for your kind offer.

Les, I have used your method on previous occasions but usually only for a simple single radius type of job. I did not fancy doing four corners and getting the groove width and positions of the straights and curves anywhere near right without a lots of material to practice with. I have usually hand held and hand fed the job whilst rotating round a pivot pin. With care

Frank, I deserved that. Dropped myself right in it there!

Thanks all

Ian P