long hole with a short drill?

[Skyrocket]

hi chaps, yes another video , can anybody suggest a way of drilling a deep hole in aluminium with the drill bit I have? regards chris

[krv3000]

well you will need a nuther drill to mod mack a extenshon bar up get a bar thats undre the sise of the drill as the drill you have is a big one turn dawn the taper on the back of the drill get your rod and drill it to fit on the bit that you have just turnd dawn on the opeset end of the rod  you can by or mack a morce taper the same sise as the origenel one of the drill and mack it fit on to the end and then weld the drill on to the rod and the taper once that is dun you cut or grind  thruw the bottom of the drill  for the flloots of the drill to let the cutings cum out hope tha macks sence sos i did not look at the vid  any way you is on the right track but with the drill you have shown in the vid you will need one or even two drills moding as the drill you have is wat as nown as a core drill its made to folow a egsisting hole tis like a end mill and a slot mill you can drill with a slot mill  but not a end mill if you keep every thing on center when you mod the drill all will be ok we have lods of them at work the way they are dun at work is the drill and the extenshon is a good fit then they drill thruw the extenshonand drill and pin thr two together 

[Jonny]

You will need to make the clamp first, tighten the two halves together then work it.

Sure you would have enough drill quill movement?
Depends how good a job you can get away with, I certainly wouldn't risk drilling through from each end, sods law it wont line up.

Other options drill through both ends with smaller dia drill then bore through on your lathe with a long boring bar between centres.

Other way use that 20mm bull nose cutter, offset either side but reduce the depth. Would leave a ridge but could take another pass. Ridges easily sanded out with smaller dia bar wrapped up with wet and dry/silicon barbide paper to make up diameter. Mind don't role the edges.

[Skyrocket]

 krv300 thanks,( sorry I don't know your name?) I do like the idea of machining a mt3 down to a mt2 so I can fit a extension piece, i may "practice" on a old bit lol
has anybody done it?

 Jonny ,quill travel is about 150 mm if I remember, its a good drill. in fact i bought it specifically for this job, i got it from a dealer who in turn had bought it from a school where it had sat for years in a "sewing room" the room once being a tech room, but i guess wood /metal working skills aren't taught much now?
so it hasn't seen much action,
I've had  a few answers on YouTube and they seem to be leaning towards line boring
 I like the idea of offsetting the bull nose cutter, i didn't know that,

[vintageandclassicrepairs]

Hi Chris,
Maybe an alternative method to wind up with what you are trying to achieve is this????
Quite a lot of motorcycle front forks have 35mm legs, so the alloy sliders have a nice 35mm bore already in them,
Split one in two on a band saw or get two and machine each to half
These should be cheap from a bike breakers

The other method I thought of is to use your 20mm ball end mill to machine a half circle full length on each piece,
Then clamp together and mount  in the lathe, centre up and then drill 35 mm as far as you  can from one end
Reverse the plot and clamp a 20 mm piece between the two halves, use this as a guide to clock up that end of the piece, then drill out to size
A 35mm drill should not have wandered a significant amount

HTH
John

[redhunter350]

Hi Skyrocket, Consider purchasing a Morse taper extension then machine down part of the female end so it is just under the drill size you are using. These are about £10 from Arc euro trade, don't know how hard they are but probably machinable with carbide or maybe HSS. You will need to weigh up the sizes to evaluate whether this will work but I have seen it done. You may also be able to use the same socket for your pilot drill as well -- depends on the MT size of both drills

No need to grind the flutes just keep clearing the drill as you proceed to depth.

If you drill does not have enough travel I would consider doing it in the lathe with a 4 jaw chuck.

Good luck with your project
John
 

[BaronJ]

hi chaps, yes another video , can anybody suggest a way of drilling a deep hole in aluminium with the drill bit I have? regards chris

Hi Chris,


The easy way as you suggest would be to mill a suitable channel in each piece of bar.
Seeing that you have a lathe and a mill,  why not make a milling cutter ?


This is how I would do it.  Obtain a short length of steel bar of a suitable diameter or a little larger.  Turn it down to the correct diameter.  Part off a disc, say 3 or 4 mm thick.  Make a spindle from a bit of 1/2" rod and mill a slot in the end to take the disc. Braze or weld the disc into the end.  Now grind a relief on opposite edges, like a spade drill, so that it will clear the work when cutting.  Heat the disc up to red heat plunge into a tin with some sugar in it.  Repeat, then dunk in water.  This will harden it.  Use like an end mill with plenty of lube.


The other way would be to put it in the four jaw on the lathe and use jubilee clips to keep it together. True it up and then drill a pilot hole as deep as you can and then use the big drill.  You will still need to use lube.  I use paraffin for alloy.


HTH.

[geoff_p]

Jonny has the answer if you combine his ideas:  Round-nose end-mill along each half, then clamp them together on your lathe saddle and open-up to size with a boring-bar between centres. 

If your lathe doesn't have sufficient between-centres (a tad over twice the length of the workpiece), then put the job on the saddle and the tool in a 4-jaw - in the video you seemed to suggest you have a long-enough boring bar.
Geoff,
Thailand

[BillTodd]

The simplest method would be to drill from both ends.However, a cheap drill press is unlikely to drill straight or square.

You could probably drill and bore on a lathe  by clamping the pieces to the cross slide and line boring (I ve used this method to make long semi circular channels for a pipe bender). You'll need a lathe with twice the part length between centres.

Bill

[BaronJ]

Hi Chris,


The easy way as you suggest would be to mill a suitable channel in each piece of bar.
Seeing that you have a lathe and a mill,  why not make a milling cutter ?


This is how I would do it.  Obtain a short length of steel bar of a suitable diameter or a little larger.  Turn it down to the correct diameter.  Part off a disc, say 3 or 4 mm thick.  Make a spindle from a bit of 1/2" rod and mill a slot in the end to take the disc. Braze or weld the disc into the end.  Now grind a relief on opposite edges, like a spade drill, so that it will clear the work when cutting.  Heat the disc up to red heat plunge into a tin with some sugar in it.  Repeat, then dunk in water.  This will harden it.  Use like an end mill with plenty of lube.


The other way would be to put it in the four jaw on the lathe and use jubilee clips to keep it together. True it up and then drill a pilot hole as deep as you can and then use the big drill.  You will still need to use lube.  I use paraffin for alloy.


HTH.

Attached drawing.  May help !