Cutting Keyways

D

deekaybell

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Hello Everyone,

I am new to this forum and hoping to find some relatively simple small projects to expand my skills base and hope that I may find some help and useful information here.

I have been machining for a little while now but consider myself to be very inexperienced. I had to upgrade my lathe recently as the motor in lathe that I had blew up and I was not able to source a replacement motor and control board. I was making a new handwheel for the cross slide of the new machine recently, which was going very well until I had to cut a keyway in the bore of the wheel. Not wanting to spend large sums of money to buy a broach kit and arbor press to do the job, I searched the internet and found a method of using a boring bar in the cross slide. It was an extremely difficult and time consuming process and the result although usable was not pretty.

This incident did however suggest a new project, "a lathe keyway cutting attachment". I was able to find a construction kit for such a device in the UK however the cost of the kit and shipping to Australia means that it would be as almost as costly as a broach kit and arbor press.

I have found a PDF of a 'lathe keyway attahment' in the downloads section of this forum but I am unable to download it. I would like to look at this file to see if it is something that I could make as I see it as a useful learning exercise. How do I get permission to download this file.

My apologies if it is at all inappropriate to post this here. I am still finding my way around the forum and likely to make a number of errors before Ihave it fully sorted out.
 
As you say its very time consuming, I use the largest dia bar that will fit the hole, grind a sharp HSS tool bit, lock the chuck so it cant turn and use the hand wheel on the saddle.
I set the cut to be at 9 o'clock and take very fine cuts.
So far they have come out pretty neat, I think the secret is taking fine cuts so the tool bit doesnt bog down.
 
I've never done it, but it's in all of the old books. It seems to me like the best way to do this technique would be using a shop-fabricated lever and pivot attachment (like a Hardinge) )for the movement instead of wearing out your acme screw and nut in the tailstock quill.
 
Here's a tool I used to broach a gear. The major diameter is the diameter of the bore, so deflection was not an issue. There is is set-screw through the shaft under the the HSS cutter to push it out as the cut progresses. I used the carriage to push it, it was hard work. Probably would have been better with the tailstock.

I've since bought a set of broaches and 3-ton arbor press, haven't needed them since.
 

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Yikes! That tool is 1/2 crazy and 1/2 genius, I just haven't figured out which is which :D I wonder if you'd be better doing that in a vise (as a cheap-arbor-press) rather than trying to use the carriage, but interesting all the same!
 
Heres how I made my indexer that also allows me to lock the chuck in position.
www.hobby-machinist.com

2016 POTD Thread Archive

Arrrrgh. Mike Rum is my poison of choice, I must have been a pirate in another life.
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post 350
and the follow on
www.hobby-machinist.com

2016 POTD Thread Archive

finished the indexer today and cut the keyway in the telescope clutch place. used a 5mm end mill/drill to cut a curved face each side of the pin to fit between the gear teeth. Not an exact fit I know but close enough and it works. I used the pimple left from parting off as an alignment aid. I...
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post 441
 
I often broach key ways in POM / aluminum gears using the (cnc) lathe. I use a self made broach from 8 mm silver steel (hardened). It only has 1 relief angle at the tip. I don't need to fixate the spindle because the 2 other edges, without relief, keep the spindle in place. I cut 0.15 mm deep in POM and 0.05 mm deep in Aluminium. The broach is only 12 mm long and at center height.
 
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