Machining problem

[piesoup]

Hello all
Just to let you know what I am using before I get into the question... The lathe is 8 x 14 with 1.75hp motor. A 4" 3 jaw chuck and a vertical slide.
Now I have dove quite a bit of 'normal' turning but have come up against a brick wall with this one!
What I am trying to do... 50mm stock of aluminium with 4 20mm holes on a 28.5mm PCD. ie. 90degrees apart.
Now, can I put my piece if ali in the vertical slide and a centre drill in the lathe chuck. Align the work with the vert slide and drill a centering hole in corect place. Then move the carrige back, replace the centre drill with a larger drill bit, drill to the correct depth. Carry on until I am nearly at 20mm, then put a 20mm endmill in the chuck. Ending up with a flat bottomed 20mm hole. Then repeat for the other 3 holes.
Is that feasable??? Or has anyone got any beter ideas!! I only have a lathe by the way, no milling machine unfortunately. I can buy a 4 jaw independent chuck if it helps.

Any ideas, advice will be greatly appreciated.
Thanks in advance!
Andrew

 

[Anglepoise]

As you are able to align everything with your vertical slide, there is absolutely nothing wrong with your setup.

That said, you might run into problems of power, belt slipping etc.
But start small and gradually creep up on the finished size with progressively larger drill bits and should work fine.

Use WD40 or kerosene to keep the drills from forming a false edge.

Good luck

 

[precisionworks]

I'd be glad to do that one for you on my mill, no cost to you except the shipping. My closest end mill is .750" (20mm = .788"), so I'd need your end mill to get to the correct size. Probably take a day or two after receipt. PM if interested.

 

[trout]

Not sure if this is universal but all my endmills have a slightly concave end and leave a convex bottom to the hole . and as I suspect you are wanting to put a led on a star there you will need to flatten the bottom

 

[piesoup]

Thanks for everyones input! I am just going to have a go and see what happens! Waiting for my vert slide to arrive, then I'll let you know how t went.
PW, thank you so much for offering your services, but if I dont do it myself I'll never learn. :thumbsup:
Anglepoise, just seen your site, love the Ti flashlight!
Chris, I have seen ONE flat endmill. Only one! But I know its out there, now just got to find it! :lolsign:

 

[tino_ale]

[...] with progressively larger drill bits[...]
Good luck

Just for my information, i thought one should not use progressively larger bits, since it tends to make oval holes... and use the right size right away : is my information wrong?

 

[Anglepoise]

Just for my information, i thought one should not use progressively larger bits, since it tends to make oval holes... and use the right size right away : is my information wrong?

I have not experienced oval holes when drilling large diameter so look forward to other comments. I have always used a fresh centerdrill / countersink and then a progression of drills till I get to the size I need. The only time I have problems getting a decent shaped hole is in sheet stock.

If the drill lips are not of equal length, from poor sharpening, then you will get an oversize hole, but oval is new to me.

 

[loneranger]

Just for my information, i thought one should not use progressively larger bits, since it tends to make oval holes... and use the right size right away : is my information wrong?

I never had a problem with oval holes before. If you have encountered oval holes, have you considered using a reamer?