Help drilling A hole
- Thread starter spurgear
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Help Support Home Model Engine Machinist Forum:
What exactly is the problem? drill is in the tailstock but doesn't seem to cut? Drill bit goes into a spiral as soon as it touches the work? What is the shaft being drilled made of? What is the drill made of? The more info the better.
goldstar31
Well-Known Member
Unfortunately, your problem is not fully explained to me.
If you are wanting to drill into the side of a piece of round bar- and not in the end, drills- be they ordinary or Slocombes( center drills) will spiral and probably break. So I'd drill a flat with either a slot drill or end mill before centring with a Slocombe and then a normal drill.
If I've got the picture wrong, I apologise
Cheers
Norman
If you are wanting to drill into the side of a piece of round bar- and not in the end, drills- be they ordinary or Slocombes( center drills) will spiral and probably break. So I'd drill a flat with either a slot drill or end mill before centring with a Slocombe and then a normal drill.
If I've got the picture wrong, I apologise
Cheers
Norman
Or make a cross-drilling jig. Take a piece of square bar and drill a hole through it lengthways the same diameter as the shaft you wish to cross-drill. Then using the drill you want to use to drill the cross-hole, drill a hole crossways in the square bar. This should be started with a centre drill or at least a centre punch mark to make sure it drills where it is supposed to.
Then you can hold the square bar in the mill vice, insert the shaft to be drilled and then drill down through the existing drill jig hole and shaft in one smooth movement.
A 2mm drill bit wants to be spinning at 2500 rpm or so. Go too slow and it can grab and break too easily. Go too fast and it will burn the end off the drill.
A bit of care in making the jig will ensure the cross-hole is dead on the centre line of the shaft to be drilled. Easy way is to lock the mill table and have the vice bolted down solid. Stand square bar upright to drill the lengthways hole. then lay the bar down flat, but with the SAME face against the fixed jaw of the vice and drill the cross hole. Thus, centre lines of both holes are in the same plane.
No need for hardened drill bushings etc for a one-off or even a 10-off job. Ordinary mild steel will do just fine for low volume work.
Then you can hold the square bar in the mill vice, insert the shaft to be drilled and then drill down through the existing drill jig hole and shaft in one smooth movement.
A 2mm drill bit wants to be spinning at 2500 rpm or so. Go too slow and it can grab and break too easily. Go too fast and it will burn the end off the drill.
A bit of care in making the jig will ensure the cross-hole is dead on the centre line of the shaft to be drilled. Easy way is to lock the mill table and have the vice bolted down solid. Stand square bar upright to drill the lengthways hole. then lay the bar down flat, but with the SAME face against the fixed jaw of the vice and drill the cross hole. Thus, centre lines of both holes are in the same plane.
No need for hardened drill bushings etc for a one-off or even a 10-off job. Ordinary mild steel will do just fine for low volume work.
Slocombe (centre drills) should NOT be used for drill centre spotting, they have the same tip shape as a standard drill and will wander off course and break the tip at the first opportunity, leave them for putting centres into work-pieces AFTER you have used a spotting drill.
Purchase a set of 90 degree spot drills up to say 8mm and they (if you take care of them) should last you for many years. They have a very special ground tip on them that cuts straight into the material without wandering.
This is where I get mine from
http://www.engineeringsupplies.co.uk/drills-carbide-cobalt-c-201.html?page=2&9=172
John
Purchase a set of 90 degree spot drills up to say 8mm and they (if you take care of them) should last you for many years. They have a very special ground tip on them that cuts straight into the material without wandering.
This is where I get mine from
http://www.engineeringsupplies.co.uk/drills-carbide-cobalt-c-201.html?page=2&9=172
John
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goldstar31
Well-Known Member
John( Blogwitch) is correct. My thoughts went to the possibility of having to drill say a casting( where a jig would be pretty futile) or to go off centre( say to make clamps), then a mill drill to create a flat seems perfectly normal engineering practice.
Of course, there are literally millions of ways to create 'steadies' for wobbly drills. Mine, I hope, was recommended to be useful in a very flimsy Unimat SL1000 which is what the poster possesses. I've used one- and still have a MJ189 which is a Unimat clone.
I tried to answer what probably is the problem with my own practical experiences in mind.
Somewhat whimsically
Norman
Of course, there are literally millions of ways to create 'steadies' for wobbly drills. Mine, I hope, was recommended to be useful in a very flimsy Unimat SL1000 which is what the poster possesses. I've used one- and still have a MJ189 which is a Unimat clone.
I tried to answer what probably is the problem with my own practical experiences in mind.
Somewhat whimsically
Norman
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f you centre pop the shaft and line up by eye to spot then adjust as necessary and drill thru.You would not normally drill anyway without a centre pop/punch
Yeah those pictures would have gotten you an answer in minutes. Find center, spot drill, and drill through Is the obvious answer.
goldstar31
Well-Known Member
I seem to be helping----so!!!!!!!
I can see now and also that you have no measuring gear to speak of on your little Uni. No matter. Sandwich a thin rule or whatever between your drill and the work. If you have got it right, the rule should be held in a horizontal plane. If not, adjust things until they are.
It also works for setting lathe tools.
Yea man, I have better 'toys' but that hasn't always been so.
Hope this helps-- and thanks for the 'likes'
Cheers
Norman
I can see now and also that you have no measuring gear to speak of on your little Uni. No matter. Sandwich a thin rule or whatever between your drill and the work. If you have got it right, the rule should be held in a horizontal plane. If not, adjust things until they are.
It also works for setting lathe tools.
Yea man, I have better 'toys' but that hasn't always been so.
Hope this helps-- and thanks for the 'likes'
Cheers
Norman
spurgear
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Yea the measuring gear is much larger than the lathe, heck i can hardly see the lathe or mill with a 6" caliper in my right hand. My Neighbor is a machinist, invited him to join this group gave me the idea for lathe bit adjustment, works great, should of realized it may work here also.
You must be an old school guy !
Thank you, Norman, great help here.
You must be an old school guy !
Thank you, Norman, great help here.
goldstar31
Well-Known Member
You must be an old school guy !
/QUOTE]
Saturday marks my 86th birthday but there was another guy that would be same age called Rex Tingey. He wrote a little book called 'Making the Most of a Unimat'. Probably on the Unimat forum but whatever, it will be really useful to you. Also there is one by a Gerald Wingrove. Guy made model cars.
All our yesterdays- or mine
Liked your little 'graduated' set square. Very useful. Learned something new to me today!
Regards
Norman
spurgear
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Thank you Norman. I have mfgd several option parts for R/C racing vehicles, at 63 I am having the the most fun allowed with the 2 Unimats, I like thinking of all the Gents here as mentors, I do so miss my father, could have learned a lot more, however you fellows are GREAT
Thanks agian
Bobby Shores
Thanks agian
Bobby Shores
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Hi Spurgear
I have been doing this type of drilling for years. First the drill is much to long, you should be using a split point short jobbers drill look online mcmaster.com. No pilot needed. Start drill with very light pressure, as soon as you get a chip go right through. As long as you are in the center of the shaft, you should be fine. Use cutting oil.
Jack
Draw-Tech
I have been doing this type of drilling for years. First the drill is much to long, you should be using a split point short jobbers drill look online mcmaster.com. No pilot needed. Start drill with very light pressure, as soon as you get a chip go right through. As long as you are in the center of the shaft, you should be fine. Use cutting oil.
Jack
Draw-Tech
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goldstar31
Well-Known Member
Initially, I can only agree with the theory but in practice we have two( perhaps more) problems.
The first is that our poster is using an early Unimat and holding a conventional drill with probably his only reasonably practical tool i.e. a Unimat 3 jaw scroll chuck. The second is rather more pointed( pun intended) and that is in the UK- where the H**** does one buy split point drills?
OK, I have the facility to 'make' the suggested tooling but not the inclination now. I have happily never been subject to the rarefied atmosphere recommended, might I suggest that we continue to assist in helping our poster- with the facilities that he has got- and not what might be available- but to others. :hDe:
Regards
Norman
