Author Topic: boring a compound angle in a block?  (Read 11597 times)

Offline shipto

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boring a compound angle in a block?
« on: October 14, 2015, 04:51:12 PM »
I need to bore a hole into the end of a aluminium block which is 85 x 65 x 40 but it needs to be 25 degrees one way and 33 degrees the other way. I have a 4 jaw chuck and a faceplate to play with but not a clue how I am going to hold the block securely enough to bore the hole.
would appreciate any ideas.
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Offline awemawson

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Re: boring a compound angle in a block?
« Reply #1 on: October 14, 2015, 05:23:09 PM »
You need a 'compound sine table' like the one illustrated below.

Now that one is a fairly expensive bit of kit - perhaps you can jury-rig something similar

An alternative is the compound vice also below
Andrew Mawson
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Offline Lew_Merrick_PE

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Re: boring a compound angle in a block?
« Reply #2 on: October 14, 2015, 05:33:17 PM »
It sounds as if you wish to bore this hole using a lathe -- which is almost certainly a non-starter.  However, as Awemawson suggests, a compound sine plate would normally be the preferred method.  My approach would be to set-up the (say) 33° angle on my tilting table (using a precision machined triangle to dial in that angle) and support it on a pair of precision machined triangles to set the 25° aspect.

What I do is to make triangles out of 6 inch X .250 inch bar stock.  I drill & ream PF holes for (ø.1875 inch) dowel pins at 5 inches on one (.250 offset) "edge" and a third hole at (6.000, 6*tan(angle) and then mill my (.250 offset) edges from the dowel pins.  I make them in pairs, steel stamp the angle on them and store them in a box/rack for re-use.  I then have a number of lengths of ø.500 bar that are reamed SF for my dowel pins such that I can coordinate the pair when necessary.

Does this help?

Offline philf

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Re: boring a compound angle in a block?
« Reply #3 on: October 14, 2015, 05:40:12 PM »
Much easier to set up in a milling machine with a tilting vice set to one angle and the work tilted in the vice at the other angle. (Or a compound vice like Andrew suggested)

I can't see how a 4-jaw would help.

In the lathe a tilting angle plate fastened to your faceplate set to one angle then clamping the work to the angle plate at the other angle could do the trick.

Phil.
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Offline shipto

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Re: boring a compound angle in a block?
« Reply #4 on: October 14, 2015, 07:00:37 PM »
I agree setting it up on a milling machine would be best unfortunatly I dont have a mill yet. maybe I could set it up on the works pillar drill if I can find a reamer the right size i need? will have to look into that.
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Offline sparky961

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Re: boring a compound angle in a block?
« Reply #5 on: October 14, 2015, 08:10:56 PM »
I'm surprised no one has asked yet about the level of accuracy you require.  If you're talking fractions of a degree then certainly a sine bar/plate setup is the most likely candidate.

However, if you can live with it being off by maybe a degree of two you can probably set things up using a plate protractor and/or a magnetic dial protractor (Google it).  A universal bevel protractor will get you even closer.  Carefully shim things up to the angles required, making sure that it's well-secured at the same time.  Light cuts and lots of clamps.  Aluminum cuts like wood if you're careful.  You may be able to get away with using wood as shims or cut the compound angle out of wood on another tool (compound mitre saw, table saw) and use it as a mounting base.  Hell, you could even cut something from aluminum on one of those.

Depending on your lathe, you may be able to secure the works to the cross slide.  If it's a through hole, consider line boring.  If not, it may still work with an adjustable boring head in your 3/4 jaw chuck.  Did I miss the size of the hole?  Maybe you can just drill it?  I like this thought much better than the whole mess spinning on a face plate.

Again, make sure it's secure and don't go blaming me if you get it in the teeth... :P

Offline PekkaNF

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Re: boring a compound angle in a block?
« Reply #6 on: October 15, 2015, 01:07:54 AM »
Sounds like one thing I needed to to put few holes. But the offset angles were a smaller, like 15 and 5 degrees. I did not have a tilting vice. Therefore I need a plan on how to make a slated "cube" that could be clamped on plain vice and milled the angles needed. Pretty easy to set up with proctractor about 1 degree of accuracy, when two opposite clamping surfaces we milled, they were used to set pice square on table and another angle was set, clamped and then all features were milled, holes put. last thing was to mill off all previous clamping surfaces, but one!

Can you chuck a whole bit bigger piece on the chuck?

Maybe you could use reverse method: First bore a hole on oversize piece (surface on hole axis if needed), maybe also turn boss or something to help successive operations and then remount and turn excess off to produce the exterior of the part with hole in correct angle, relative to lathe chuck (or turning axis).

Might need some thought before and tapping/drilling holes to mount it on a "dolly" that could be chucked on four jaw chuck?

Pekka

Offline chipenter

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Re: boring a compound angle in a block?
« Reply #7 on: October 15, 2015, 04:25:14 AM »
Clamp it to an angle block to the greater angle , mount it on the compound slide and turn the compound to the required angle , or use a test bar between centres .
Jeff

Offline shipto

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Re: boring a compound angle in a block?
« Reply #8 on: October 15, 2015, 04:58:19 AM »
Accuracy isn't critical basically it's a block to mount carbs on a dirt bike that I am fitting a engine that was meant for a different bike. This has meant that the direction the carbs mounted needs to be reversed. So as long as the carbs are close to horizontal it will be fine. I think I might try to weld up a jig today that I can put on faceplate.
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Offline Jonny

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Re: boring a compound angle in a block?
« Reply #9 on: October 15, 2015, 08:42:30 AM »
Easy on in a lathe, bore through parallel a larger block of aluminium. Mill to size after job done easy.
Don't forget to extra boring lengths.

Did one last week but in mill, just angled it in a vice.

No bolt holes for carb, reed or barrel fit?

Offline shipto

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Re: boring a compound angle in a block?
« Reply #10 on: October 15, 2015, 11:05:01 AM »
Yeah should have bored hole first but lack of forward planning got me again. However I think I have it sussed now. The reed is sandwiched between this adapter and the engine and the carb will slot into this hole I am boring with o ring to seal it and I need to work out a way to secure it which may be doing something from airbox not sure yet
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Offline Jasonb

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Re: boring a compound angle in a block?
« Reply #11 on: October 15, 2015, 02:07:01 PM »
I tend to use a pair of angle plates for things like this. Clamp one angle plate to the lathe cross slide at 33degrees to the lathe axis. Bolt another angle plate to that which is tilted 25deg from horizontal and clamp your block to that. Drill out most of the waste and finish with a boring bar

Offline DMIOM

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Re: boring a compound angle in a block?
« Reply #12 on: October 15, 2015, 02:41:54 PM »
especially if you're going to start drilling out the waste, would suggest you use a slot-drill or other end-cutting milling cutter to produce a flat spot first, otherwise when you try with a conventional twist drill its likely to skid off-line and/or grab your workpiece.

Dave

Offline PekkaNF

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Re: boring a compound angle in a block?
« Reply #13 on: October 15, 2015, 03:51:42 PM »
But if he is boring this on lathe, flat is easily turned.

Pekka

Offline Jonny

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Re: boring a compound angle in a block?
« Reply #14 on: October 15, 2015, 05:06:52 PM »
The reed is sandwiched between this adapter and the engine and the carb will slot into this hole I am boring with o ring to seal it and I need to work out a way to secure it which may be doing something from airbox not sure yet

Surely an adaptor with flange to suit the reed valve with stand off to suit o/d of carb via silicon tube way to go. Just start of adaptor make the leading edge sharp from bore of silicon.
Then could attach to carb with something like a Mikalor and same to air box.

From memory these adaptors have moulded sections to them giving correct angle. Yours you would have to machine front face at that desired angle.
Whilst at it smooth out prior to the reed usually pretty good any way.

What engine is it, SX, KX, CR?

Offline shipto

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Re: boring a compound angle in a block?
« Reply #15 on: October 15, 2015, 05:26:32 PM »
Its a Yamaha yz250 engine which I am shoehorning into a cheap chinese ?suzuko? frame and basically I am using what I have to hand as its a favour for a friend who doesnt like spending money  :lol:
Although I do need to restart a different way as I worked out tonight that there is no way to bore this hole the correct angle without breaking through the sides so its back to the drawing board even though I managed to figure how to do it  :doh:
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Offline Manxmodder

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Re: boring a compound angle in a block?
« Reply #16 on: October 16, 2015, 07:37:28 AM »
I'm fairly familiar with Yam 2 stroke engines from past ownership.

What is the original Yamaha intake adapter made from? If it's ally then maybe you could cut the inlet part of and  turn it 180 deg and re-weld.

If it is the nitrile rubber type inlet then perhaps a new one could be fabricated from tubing and sheet metal,tacked together with a mig and a bit of grinding and fettling to arrive at the desired shape.....OZ.
Helixes aren't always downward spirals,sometimes they're screwed up

Offline shipto

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Re: boring a compound angle in a block?
« Reply #17 on: October 16, 2015, 03:55:43 PM »
I'm fairly familiar with Yam 2 stroke engines from past ownership.

What is the original Yamaha intake adapter made from? If it's ally then maybe you could cut the inlet part of and  turn it 180 deg and re-weld.

If it is the nitrile rubber type inlet then perhaps a new one could be fabricated from tubing and sheet metal,tacked together with a mig and a bit of grinding and fettling to arrive at the desired shape.....OZ.
Its the rubber one and funnily enough I have solved it exactly as you said, great minds think alike.. even though mine takes a while to catch up  :lol:
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Offline Jonny

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Re: boring a compound angle in a block?
« Reply #18 on: October 16, 2015, 06:20:09 PM »
I would beef up his frame as well.
Back in 79 was running 49hp with a KX on par with the 490 YZ in late 81.


Offline Arbalist

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Re: boring a compound angle in a block?
« Reply #19 on: October 17, 2015, 07:31:33 AM »
I've used this setup in lieu of a tilt and swivel vice.



I'd still like a T&S but they can take up a fair bit of your Z on a mill.

Offline shipto

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Re: boring a compound angle in a block?
« Reply #20 on: October 20, 2015, 04:13:51 PM »
I've used this setup in lieu of a tilt and swivel vice.



I'd still like a T&S but they can take up a fair bit of your Z on a mill.
Thats a neat solution  :thumbup:
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Offline Jonny

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Re: boring a compound angle in a block?
« Reply #21 on: October 21, 2015, 04:58:31 PM »
Just clamp the job in the vice at an angle, no messing about.
Its only if need to be super precise need any other means.

Round items done almost daily for last 22 years, drilled through on curves and radiuses.
Heres a sample ploughed straight in.
http://pic20.picturetrail.com/VOL15/728921/1252422/411770044.jpg
http://pic20.picturetrail.com/VOL15/728921/1252422/411770000.jpg
http://pic20.picturetrail.com/VOL15/728921/1252422/411770046.jpg
http://pic20.picturetrail.com/VOL15/728921/1243489/398674434.jpg
http://pic20.picturetrail.com/VOL15/728921/1243489/393859052.jpg

Offline Will_D

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Re: boring a compound angle in a block?
« Reply #22 on: October 21, 2015, 05:33:29 PM »
Johny, Lovely work but all those holes are at 90 degrees to the work piece. Surely this thread is about holes that are not  orthoganal to a plane?
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Offline Arbalist

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Re: boring a compound angle in a block?
« Reply #23 on: October 22, 2015, 05:46:09 AM »
Thats a neat solution  :thumbup:

It's far easier to set the vice at an angle, especially if you're machining small parts. It's also much quicker and more accurate if you have several parts to machine/drill all at the same angle. You can also do compound angles By clamping the part at an angle.

I made my tangential tool with this setup. I only have a plain vice so I had to slew it around 12° on the mill table then clamp the small vice in it at 12°.