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Mr-Mike
02-21-2016, 11:24 AM
How would one cut a small (1/16 wide) key way inside an 8mm dia bore?

Thanks!

achtanelion
02-21-2016, 11:36 AM
I'd use something like a rifling cutter box. See Post 12 on this thread. http://castboolits.gunloads.com/showthread.php?147639-Building-a-Barrel-Rifling-Machine

Jimmer12
02-21-2016, 11:42 AM
Wire edm lol. Sorry for being a smart ass.

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duckman
02-21-2016, 11:48 AM
Hack saw blade and file, tada done.

becksmachine
02-21-2016, 11:55 AM
How would one cut a small (1/16 wide) key way inside an 8mm dia bore?

Thanks!

Through hole or blind? How long? How many pieces?

Not looking at any of the other suggestions, my first thought for one piece would be to drag it out on a lathe.

If it was a through hole and not too long, I would think you could find a broach to do that? Just looked, Minute Man lists 1/16" broaches and 8mm bushings.

Dave

Mr-Mike
02-21-2016, 12:13 PM
1/2 inch long, through.

Thanks for the suggestions!

DR
02-21-2016, 12:23 PM
If it was a high dollar part I'd take it to a local shop with the broach and bushing.

If it wasn't so high dollar either lathe or mill to nibble the keyway.

mars-red
02-21-2016, 12:48 PM
I'll second the lathe method, it works pretty well if you're careful to keep the cuts really light. I once put "ears" through a hole using the same method:

https://lh3.googleusercontent.com/-5VqDXWMvefc/ULZHswlUnrI/AAAAAAAACaA/ApQNyYyYz1s/s960-Ic42/broached%252520bed%252520attachment.jpg

Jimmer12
02-21-2016, 01:13 PM
If it was a high dollar part I'd take it to a local shop with the broach and bushing.

If it wasn't so high dollar either lathe or mill to nibble the keyway.
If it was a high dollar shop, I'd take it to a wire edm shop personally.

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Mr-Mike
02-21-2016, 01:22 PM
Neat stuff guys. Learned something here today, as I always do.

Thank you!

Rosco-P
02-21-2016, 01:23 PM
Hack saw blade and file, tada done.

+1 to the above.

olf20
02-21-2016, 01:26 PM
I just had to put a key in my new pulley for the mill.
I used a cutoff blade laid flat on my QC tool post.
Just went in and out a few dozen times.
Poof - Key way.
olf20 / Bob

drmico60
02-21-2016, 01:46 PM
How would one cut a small (1/16 wide) key way inside an 8mm dia bore?

Thanks!

I have used a small adjustable broach to make keyway slots in small bores, see:
http://mikesworkshop.weebly.com/small-hole-slotting-tool.html

Tool is simple to make.

Mike

RussZHC
02-21-2016, 01:54 PM
The lathe method(s)...I have only ever seen examples using a single edge tool/bit.

Is there any reason someone could not make up a multi edge tool, sort of like a home made broach?
Though not as long, I mean if you have brazed your own tools at some time, too time consuming for any of the perceived gain?
(20 back and forth movements on the lathe may take less time and effort than the time to make up something multi-toothed and do three passes say)

I could also see how having the older style of boring bar, the ones with the HSS lathe bits used as cutters, would be handy, change the shape of the edge and away you go.

mattthemuppet
02-21-2016, 03:04 PM
I have used a small adjustable broach to make keyway slots in small bores, see:
http://mikesworkshop.weebly.com/small-hole-slotting-tool.html

Tool is simple to make.

Mike

that is such a cool idea, I'll park that in the brain for future use!

Joel
02-21-2016, 04:25 PM
I have used a small adjustable broach to make keyway slots in small bores, see:
http://mikesworkshop.weebly.com/small-hole-slotting-tool.html
Tool is simple to make.


Cool idea. I hadn't seen that method before, of if I have, I have forgotten it!

I wonder - perhaps one could put a groove near the tail end of the cutter and use an o-ring for a hinge (easier than using a pin). Spring load the front (a small scrap of spring steel would do) and it would retract on the back stroke, so only a depth increase would require the allen key. Plus, it would stop the jamming you mentioned. More cutter angle and some relief might work a little better. Leave plenty of space up front to keep chips at bay, and a boring bar holder could be used.
'Course, the added work would only pay of with several parts to do, and slotting by the more traditional method isn't all that difficult either.

rkepler
02-21-2016, 05:49 PM
1/2" long and through? If that isn't made for broaching I don't know what would be. That's a 1 minute job and half of that is sorting the guide bushing.

bytewise
02-21-2016, 07:35 PM
That is a natural job for a small shaper. I have an Atlas 7" shaper and cut 1/16 keyways in 3/8" bore gears for my model machine. I use part of a 1/16" cutoff blade as the cutter.

Rosco-P
02-21-2016, 08:37 PM
That is a natural job for a small shaper. I have an Atlas 7" shaper and cut 1/16 keyways in 3/8" bore gears for my model machine. I use part of a 1/16" cutoff blade as the cutter.

By the time you've set up the shaper to cut a single keyway in a single part, a skilled person using two different files or a hacksaw and a single file would be done.

CCWKen
02-21-2016, 09:21 PM
I don't know what kind of hacksaws you guys have but none of my blades will fit into a 8mm hole. :confused:

Rosco-P
02-21-2016, 09:53 PM
I don't know what kind of hacksaws you guys have but none of my blades will fit into a 8mm hole. :confused:

Use a jewelers saw or just cut down the edges of the keyway with an appropriate shaped file and hog the remaining material out with a file with safe edges.

Rich Carlstedt
02-21-2016, 10:13 PM
Take a broken tap and make a broach .
mount it in a 5C block with the table set for a relief (ie 92 deg)
Mark parallel lines on the table for guiding.
Use an ice cube to hold the tool against the belt . Grind with the cutting edge down, not up !
The ice will prevent over heating the delicate tool bit.

set the tool in the mill collet without power, and manually broach the key-way, moving the Y axis .001" at a time .
Simple ..you could use a lathe as well/

Here are some pics to give you an idea.
Also broach square holes.

Rich

http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20tales/P3280059_zpssrgclczl.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20tales/P3280059_zpssrgclczl.jpg.html)
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/PC270068-1.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20Tools/PC270068-1.jpg.html)
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/BroachingPC270071-1.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20Tools/BroachingPC270071-1.jpg.html)
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/PC270069.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20Tools/PC270069.jpg.html)

Rich Carlstedt
02-21-2016, 10:14 PM
And a square hole
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/PB100019.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20Tools/PB100019.jpg.html)


On the broach, you can see how long the broach can be made.
The .030 broach was used in a hole that was .187 in diameter


Rich

Mr-Mike
02-21-2016, 10:51 PM
Nice Rich!

ahidley
02-21-2016, 11:21 PM
I used my lathe to make a keyway on a stihl leafblower that was on a tapered aluminum flywheel that sheared off
It worked great.

Jaakko Fagerlund
02-22-2016, 11:21 AM
By the time you've set up the shaper to cut a single keyway in a single part, a skilled person using two different files or a hacksaw and a single file would be done.
Have never seen a hand filed keyway that is within specs. The tolerances on this size keyway are beoynd filing.

Rosco-P
02-22-2016, 11:44 AM
Have never seen a hand filed keyway that is within specs. The tolerances on this size keyway are beoynd filing.

First of all, we're talking one keyway on a part that's probably not destined for the next Mars Rover.

Secondly, you haven't seen some of the handwork my machinist neighbor did. Machinist his entire life, passed away in his 80's taught machinery design, worked for Nabisco, Atlantic & Pacific Tea Co and others, partner in a medium sized machine shop after retiring, defense work for the Navy, etc.