Ball nosed slot drill

Yes makes sense and you are correct.

-- Regards,

John Stevenson Nottingham, England.

Hi Simon

Your logic is sound but it seems like a very expensive solution if it's just for a 'one off' Could you not simply fly cut the profile into the bar?

Regards

--

Chris Edwards (in deepest Dorset) ..."There must be an easier way...!"

That, or if it's only a few inches long, set it in the 4-jaw and use a boring tool. Or, clamp it to a vertical slide and use a between-centers boring bar.

ChrisH

Thanks all for replying and checking my logic.

I had thought about mounting the bar off center in a 4 jaw or using a fly cutter as suggested. I agree this would be the longer term solution and should allow me to do other radii without the expense of different size slot drills.

However I am novice to metal work, and my mini lathe, of only about 3 months, so I don't have some of the standard tooling, and skill, available to me ;)

looking at the price of a 4 jaw chuck and needing to get this particular job done soonest without a good deal of practice I am going to go with the slot drill approach this time.I think this will give me the best chance of achieving the result I need.

When I have a bit more time and money to invest I will put the practice in with the other methods.

Once again many thanks for all the suggestions.

Best Regards,

Simon

Simon, A 20mm ball-nosed cutter requires a sturdy mill for it to cut - even in aluminium there will be a lot of vibration. What machine are you proposing to use for this job? I think you'll be disappointed if you try it on a light-weight machine.

A between-centers boring bar is easy and quick to make. Just take a length of 1/2" round steel bar and drill a 3/16" hole cross-wise in the middle of it. At 90deg to that drill and tap for a setscrew. Now you can grind up a cutter from 3/16" HSS rod and set the point so it is at 10mm radius, and hold it there with the screw. Clamp your ally bar to a vertical slide (or angleplate, or just pack it up to center height on blocks). You will find it much easier on the machine to make the cut with a single-point tool than with a ball-nosed cutter.

ChrisH

To add to that - given the small lathe I think you might end up having problems with getting a decent finish on the groove with a ball-nosed cutter.

Regards,

Chris,

My workshop breifly consists of a small 7 x 12 mini lathe from chester UK(

A reasonably sturdy floor standing drill press and an old bench grinder.

I hadn't thought about the size of the slot drill and the problems this might cause. The 7x12 mini lathe has one of the mini milling attachments. So far I have only used this with a 2mm end mill in stainless steel. It coped quite nicely.

Thanks for the info on the between centers boring bar. It sounds mostly within my skill level but i haven't made my own cutting tip yet. There does seem to be a lot of info about doing that on the web so I'll have a good read. It would be handy to have a crack at this for the future.

Would the lathe and the milling attachment be sturdy enough to cope with the

20mm cutter or had i better buy some some steel, and get more aquianted with the bench grinder?

Best Regards,

Simon

Not really. Another problem on a cutter this size would be holding it. A 20mm cutter will be on a 20mm shank or possibly 19mm. Holding a cutter this size in a chuck is a definite no no, it will walk out. An end mill holder or collet chuck for this size will not be available for your machine.

-- Regards,

John Stevenson Nottingham, England.

I'd baulk at it even on my Maximat V10. Besides, turning between centres is fun! Honest!

Regards,

Well im convinced to ditch the slot drill idea now. the steel is on order and i have some reading to do ;)

Thanks all for the advice. I'll let you know how i get on.

Best Regards,

Simon

Hi Simon, Noting your confession as a beginner, could I suggest you buy,beg or borrow a copy of 'The Amateur's Lathe' by L Sparey. It is quite an old book that comes in and out of print but it it gives lots of tips and ideas of how to achieve a wide variety of operation in the lathe including milling.

£8.69 posted from Swotbooks.com is the cheapest according to kelkoo

Best wishes for your progress in this most rewarding of hobbies regards

Bob

Good call! Absolutely seconded - it's book you'll never regret buying.

Regards,

Bob,

I had a look around an eveyone seems to love this book. Sugeestion readily accepted. It too is on order.

Thank you for the best wishes.

Im cursing a lot at the moment when i ruin a part thats taken a day or two to get to that stage. I have managed to get some parts just how i want them and it is most satisfying. Especially after some ignorance has been removed to make the part as well as chips ;)

I have a feeling Im hooked.

Simon

attachments.

Jup! It does sound rather like you are in for a life sentence!

Good luck

Bob

>

The best feeling around. Bar one of course.

Have you experienced the frying bacon yet. Must be one of the most satisfying sounds there is when machining.

Another good man joins the club. Welcome and don't fight it, just go with the flow and enjoy! Wait till you steam and run your first loco. Amazing feeling. GeoffH