Keyway with shaper

benmychree said:
Yes, you do have to lock the clapper box, the tendency is if cutting on the bottom the tool wants to rise due to it's distance from the pivot point of the clapper and in cutting on top the tool wants to rise and bind up in the cut. Look at the clapper box on nearly any shaper; there are setscrews usually on both sides of the clapper box, with matching divots in the clapper to lock it down, they are there for a purpose. I just read a chapter in Lewis E. King's book Machine Shop Operation booklet #3 Shaper Operation, published by Macmillan, that sometimes keyway cutting is done on the return stroke rather than the normal cutting stroke, I wonder that it may be better to pull the cut than pushing the cut, that is what keyseaters do.
Click to expand...

Sadly, my shaper seems to not have said set-screws or any similar locking mechanism.

I guess my question was mostly further clarification to this: "due to it's distance from the pivot point of the clapper". What determines the critical distance here? Why is it not a problem on the normal tool holder?

My theory above was that it simply had enough torque to lift the clapper when pushing, however with a sufficient amount of weight placed further away from the tool (such as a super long bar, with the cutter set further back), you could get the same effect as a normal tool holder.

Or is it the ratio of 'up/down' to 'distance'? If so, do those 'drop boring bar' type holders (where it holds the boring bar in an anderson style holder) have the same problem? Could one build a sufficiently long one of those to not have that problem?
 
I watched the video, and it was for the most part OK, got the job done, but there CAN be problems with the method of using a finishing tool as he does; in a shaper in perfect condition, with a perfectly tight unworn ram and table ways, it would be possible, with any wear to those elements, you would likely end up with a tapered keyway. A full width tool for finishing would eliminate that possibility, this is what is used with keyseaters.
So far as measurement of the width, what I always use is simply an adjustable parallel set up tightly in the slot and projecting from the slot and measured with a micrometer, gage blocks are quite a case of overkill for this application, at least in my opinion. With a keyseater, cutting time would be perhaps 5 minutes for a job like that one shown on the crown gear coupling half.
 
ErichKeane said:
Sadly, my shaper seems to not have said set-screws or any similar locking mechanism.

I guess my question was mostly further clarification to this: "due to it's distance from the pivot point of the clapper". What determines the critical distance here? Why is it not a problem on the normal tool holder?

My theory above was that it simply had enough torque to lift the clapper when pushing, however with a sufficient amount of weight placed further away from the tool (such as a super long bar, with the cutter set further back), you could get the same effect as a normal tool holder.

Or is it the ratio of 'up/down' to 'distance'? If so, do those 'drop boring bar' type holders (where it holds the boring bar in an anderson style holder) have the same problem? Could one build a sufficiently long one of those to not have that problem?
Click to expand...
An illustration of the tendency of the tool to lift can be seen in the use of the Armstrong (and other brands) of shaper tool holder that can be reversed so that the tool is ahead of the clapper pivot point and when reversed so that it is further to the rear, when ahead, there can be a tendency to chatter, when reversed, the chatter goes away, this tendency is greatly exaggerated when an extension bar is used, as for keyseating. Making a very long bar as you suggest would make chatter even worse by acting as a lever arm of mass that is not supported, perhaps there is a better way of explaining it, but it is not at my command for now. There is not a problem to doing the setscrew thing to your clapper, just be sure that when drilling for the divots in the clapper that they are slightly offset to the front so that the setscrews when tightened tend to pull the clapper against the seat of the clapper box. Note that in the video, he made a point of forgetting to tighten the setscrew, for some reason, his has only one, mine has them on both sides, and it is the same brand of shaper, about the same size, although his is older than mine
 
benmychree said:
An illustration of the tendency of the tool to lift can be seen in the use of the Armstrong (and other brands) of shaper tool holder that can be reversed so that the tool is ahead of the clapper pivot point and when reversed so that it is further to the rear, when ahead, there can be a tendency to chatter, when reversed, the chatter goes away, this tendency is greatly exaggerated when an extension bar is used, as for keyseating. Making a very long bar as you suggest would make chatter even worse by acting as a lever arm of mass that is not supported, perhaps there is a better way of explaining it, but it is not at my command for now. There is not a problem to doing the setscrew thing to your clapper, just be sure that when drilling for the divots in the clapper that they are slightly offset to the front so that the setscrews when tightened tend to pull the clapper against the seat of the clapper box. Note that in the video, he made a point of forgetting to tighten the setscrew, for some reason, his has only one, mine has them on both sides, and it is the same brand of shaper, about the same size, although his is older than mine
Click to expand...


My idea of the long bar was to make the cutting tool only, say 3 inches from the front of the clapper, but leave the bar 12 inches long, such that the weight of it counteracts the tool's propensity to lift.
 
Yes, I got that, but, as I said it would exacerbate the tendency to chatter. Like any other tooling used on most any machine tools, they should be as short and large diameter as possible to avoid deflection and chatter.
 
Ah, interesting then. Thanks for clarifying!
 
My 10" shaper uses a 6" tool for doing internal keyways. I haven't had any problem with lift, but I'm not very aggressive in cutting. I wonder if cutting more aggressively can require the clapper locked, but I don't bother, and my keyways seem to be fine.

I've only doen 5 or 6 keyways on the shaper, before that I was limited to using my BP mill and using the quill. I prefer the shaper.
 
I had a BP type mill (Induma) that the previous owner had used for broaching, they managed to break a tooth off the quill rack gear, When I bought it, I had to buy a new quill to repair the damage.
Any job that you can use horsepower rather than arm power is a good thing!
 
Thanks guys, this has been very helpful. Sorta got preoccupied today but first thing tomorrow is to look for set screws. Just beginning to get acquainted with the machine and am sure it is less labor intensive than a file. The discussion about cutting the keyway on top and in reverse has sure caught my interest, in fact the whole concept is going to be the center of my attention in the next few days.
Have a good day
Ray
 
I have made a mount that replaces the toolpost and I can change bar sizes as copied from commercial bars using HSS,(like a boring bar), and also have made a couple similar to this:
with brazed in retangular HSS which I cut from an old 3 mm thick planer blade. I use the latter often as I have found that taking a pilot cut to near full depth before going to a wider tool makes the job a breeze.
I have cut with the clapper free and locked and don't notice much difference. Only cutting about 10 thou per cut.
Machine Alba-1A 10" similar to an Elliot.

Here's are a couple of old articles that may help:
 

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  • Cutting keyway with a shaper.pdf
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