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Post by SpaceCadet on May 11, 2004 17:06:07 GMT
Hello,
Anyone have a really good cross-drilling jig design ?
This is one thing I seem to do quite a lot of, any unless
I set the vertical side up in the lathe and use an edge
finder, I never seem to get it right.
Regards
Ian
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Post by Deleted on May 11, 2004 18:55:30 GMT
Hi, I to was dreaming of such a jig … never seem to have found the right one. So I sort of cheated. When I have to drill a hole trough a shaft I always file a small flat at the place where the drill should start. Then make a centre pop and start with a centre drill. Directing the drill straight true the work piece is a matter of eyesight, although I found that a it helps a lot when you scribe a line on the front of the axle. This makes it easier to put the job correct in the vice or the V block. I know, not what you asked but just my solution By the way awfully quiet here. Seems most of the lads still prefer the mail list. Regards Wilfried Vermeiren users.skynet.be/modelbouw.wilfried |
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Post by Tel on May 12, 2004 6:48:38 GMT
I do almost all of my cross drilling in the drill press - I got a piece of channel & drilled it to take two bolts that go thru' two of the slots in the table, then carefully marked it out & drilled thru the middle of the 'back' with a 1/4" drill. In use, bolt it loosely to the table, put a 1/4" rod in the chuck & bring it down thru the hole & tighten up the bolts. Now all you gotta do is lay your workpiece on top of the channel, start the hole with a centre drill, & then drill thru the size you want. Not super accurate, but adequate for most m.e. applications.
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Post by AlMesser on May 13, 2004 3:56:56 GMT
There is a good design in Workshop Practice Series No. 20, "Metalwork and Machining Hints and Tips" on Page 87.
Al
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IP
Involved Member
Posts: 72
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Post by IP on May 16, 2004 7:41:44 GMT
George Thomas in his book Model Engineers Workshop covers this topic very well indeed together with many, many more useful things. I can recommend the book. Regards.
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lancelot
Part of the e-furniture
Posts: 471
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Post by lancelot on Jul 14, 2004 20:21:00 GMT
Hello,
Model Engineer issue no/3794...vol/158...6 feb 1986....
An unusual drilling jig by A.F.Davies...
Shows a brilliant design .
It consists of two bars of metal approx/12 ins long by ,say two'' by one'' inches,these are set side by side like catamaran hulls about four inches apart,then joined together by two cross bars of four inches in length by approx/1/2'' by 3/8'' @what looks to be 1 1/2'' from each end of the 12'' bars.[hope your following this]
In the middle of the four inch cross bars position a drill bush for say 1/8'' as a fixture.
Now the easy bit,locate the pice of material that has to be centre drilled under the cross bars and between the12'' bars.Swing the 12'' bars together so as to clamp the work piece,and using the drill bush drill your bar in the centre.
You can of course use various sizes of drill bush.
I just found this yesterday in an old second hand book shop,so I will be trying this idea out myself as well.
All the best for now,
John.
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Post by jbuckley on Jul 14, 2004 21:13:33 GMT
HI all,
What I have used for e few years now is a block of cast iron mounted in place of the tool post. I then faced off one side and used a progression of a 1/16" slot drill followed by a countersink drill to from a groove which is now on centre height.
I then use a small metal strap which is screwed top and bottom to hold the round bar in place. Leave the part you want to put the hole though poking out over the lathe bed and line it up with the drill and what angle you want the hole at.
I then put a piece of brass in the tailstock drill chuch to hold the pressure on the bar as I move the carriage along. That way the carrriage is only taking up the slack rather than pushing the bbar against the drill.
I will take a photo of the holder and see if I can get it up on the photos later in the day.
I can recommend the tool as time well spent.
Regards,
John
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jackrae
Elder Statesman
Posts: 1,335
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Post by jackrae on Jul 14, 2004 21:22:31 GMT
Turn a short piece a thou or so less than the job you want to drill. Put a pilot hole through this short piece
Now clamp the job in your vice and place the short piece in top of the job with its pilot hole located above where you wish to drill the job.
Drill down through the pilot hole in the short piece and your pilot hole should go down through the centre of the job
regards
jack
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Post by Deleted on Jul 15, 2004 6:21:14 GMT
Cool, which I had dreamed this up Jack. When I use my way, see above, I usually measure so the pop gets it halfway between the vice jaws. This is way much easier. Regards Wilfried Vermeiren users.skynet.be/modelbouw.wilfried |
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Post by Roger Mason on Jul 15, 2004 9:01:58 GMT
Hi,
I think this topic came up on the old e-mail list. I was impressed with the simple idea that one of our members put up, to the extent that I copied the idea and it works like a dream.
The idea was basically the same as the idea that John has just described. It is a vee slot milled (using a countersink bit) into an angle plate bolted down directly onto the cross-slide. In this way the slot has to be at centre height. The shaft is then clamped into this slot and has to be at centre height, also.
I have used this idea recently to drill some holes in a shaft to locate valve gear lifting arms. To my amazement the pin can be inserted through the link boss and the shaft with the shaft turned 180 degrees - the most stringent test that I can think of!!
I recommend this idea to all who want to drill a cross hole that goes through the centre of a shaft.
Cheers,
Roger Mason, in St. Agnes.
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Post by AlMesser on Jul 17, 2004 2:49:08 GMT
I think that is was TEL that taught me a neat trick awhile back. Chuck up a piece of Square stock in the 4 jaw chuck, center and drill a hole same diameter as the workpiece you want to cross-drill. Scribe center line on one flat of the Square stock and center pop and drill. Insert the workpiece through the hole and drill through the hole in the flat. I drilled twenty four 1/16" dia. holes for Cotter pins in this way a while back in some 1/4" dia. stock.
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Post by AlMesser on Jul 17, 2004 2:49:51 GMT
I think that is was TEL that taught me a neat trick awhile back. Chuck up a piece of Square stock in the 4 jaw chuck, center and drill a hole same diameter as the workpiece you want to cross-drill. Scribe center line on one flat of the Square stock and center pop and drill. Insert the workpiece through the hole and drill through the hole in the flat. I drilled twenty four 1/16" dia. holes for Cotter pins in this way a while back in some 1/4" dia. stock.
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Post by Tel on Jul 17, 2004 7:11:52 GMT
Yeah Al, that's one of mine. I can (and have) cross drill 1/16" rivets for tiny split pins this way. And the beauty of it is that by carefully locating your drill hole back from the edge the rivit head acts as it's own depth stop.
Harking back to John & Roger's preferred method - the slot don't even have to be of vee shape - you can just run an ordinary endmill across your block to form a slot that will locate stock just as well, even if the range of sizes is more limited, but, guess wot? Most blocks have four sides, so you can make one that will acommodate quite a range of stock size.
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Post by Tim Bayliss on Jul 27, 2004 19:24:36 GMT
I don't use a jig, as such, for cross drilling. For longer than I can recall I've used the following method to great effect, so long in fact I can't remember where I got it from in the first place!
First clamp your round workpiece in a good vice with as much protruding over the jaws as is practically possible while still holding it solidly. Now lightly bolt the vice to the drill table so it can be nudged with a soft mallet or something similar. Install a very stiff drill in the chuck, I use a centre drill, and roughly centre it on the job by eye. Here comes the good bit - get hold of a thin piece of stuff about 6" long x 1/2" wide(150MM x12mm) which is very stiff, I have a nice 6" stainless steel rule, very stiff but also very thin. Catch the 'rule' at it's middle between the centre drill and the workpiece (the rule laying across the workpiece) by gently lowering the drill spindle, this is what you should see.
If the centre drill is off to the left of centre on the workpiece the rule will lie angled down to the left, if to the right it lay angled down to the right. Now, making sure that the centre drill is only holding the rule very lightly, tap the VICE over till the rule becomes horizontal. You should be able to judge this off the top of the vice jaws. Now nip up the vice holding bolts, use the centre drill to drill a small 'pop', replace it with your desired drill and drill away.
With a little practice and a good stiff but very thin rule I have found this method to be spot on, not close or near enough, but spot on. Give it a go on a piece of scrap!
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Post by Tel on Jul 27, 2004 21:12:30 GMT
Sounds good to me. Hadn't occured, even tho' I use a variation of that method to get lathe tools on centre height - brain must be rustin' up.
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