91 forum posts
Evening all, hope well and safe.
I need to drill a straight'ish hole In some square 6082, it will be 180mm long with a finished diameter 19mm for half the depth and 16mm for the other half. Once I have my initial hole I can bore from either end, I'm guessing with a boring bar?
Anyway I have two approaches for the I initial hole but Im not sure which to pursue. Max I have drill size is 14mm in jobber and extra long with a few other sizes the same. Using the 7x12 Clarke I can either drill half way using a cats cradle to support the stock then reverse using a M2 jobber length in the tail stock or. Mount my 250 long 14mm drill in the four jaw, mount my stock on the cross and do the entire length in one go. With this method I would turn a sleeve for the long drills and mount them in the steady about half way then remove it to drill the rest. I will in either case have to use a 7mm to start then the 14mm. I have tried going straight in with a 14mm but know dice. Max the machine is happy with is 10mm I chose 7mm to start because I find it you go to close to your finish size drill it tends to encourage wonder (not sure if that's just me). I hope this is understand.
|pgk pgk||09/05/2020 21:24:53|
|2553 forum posts|
I was toying with the idea of a project involving a 12mm blind hole 200mm deep into mild steel One of the thoughts that crossed my mind was to turn down the shank of a centre cutting HSS endmill and bond into an 11mm rod once it was full depth. It would be a slow process of keeping withdrawing and flushing/lubricating. I haven't tried it..
It might go slightly quicker with a pilot hole to 'store' some chips between withdrawals but would take a lot of 'feel for clogged flutes?
|not done it yet||09/05/2020 22:29:10|
|6744 forum posts|
A non-centre cutting end mill would suffice if a piot is drilled first. I often use an end mill to enlarge holes (or reposition, if not quite in the correct position 😀 ).
|294 forum posts|
A technique I have used to drill the spindle on wood lathes is to have the hole started on centre in the metal working lathe. Then assemble the spindle in the wood lathe and drive with the motor on SLOW speed. A 6mm twist drill with an extension shank silver brazed on that is longer than the spindle length. Chuck the drill in a hand held electric drill on low speed. Back out often to clear the swarf and keep adding cutting oil. The pilot hole came out on centre. Then used 8.5mm extended shank drill to finished size. With the drill and work both rotating in opposite directions the drill stays on centre.
91 forum posts
I took the plunge today and decided to mount the stock on the crosss slide. It has taken all day to think mainly how to get the stock centred. After some thought and many cups of coffee I finally Sussed it 💡. I turned a piece of round stock to 30mm (same as my square) it ended up 29.95mm. I set the final height of my work by planer thicknesing a piece of mahogany. With my 30mm round centred in the chuck I put the indicator on the head stock zeroed it on the top of the round stock. After removing the round i then brought my square stock to the indicator and am very close to zero. I used a piece of ground bar in the chuck to get parallel and to get centre on this axis I chucked my 30mm bar zeroed my indicator, removed the round and then fed the square in using the cross slide until I got to zero. I hope this all understandable.
After all this messing around I found my 7mm long series has been used by a certain person as an SDS! I took the amalgamation apart as a new drill will take 3 or 4 days to come. When I do again toward the week end it will probably take around 3/4 of day 😁,
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