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[machinist] Tool design for cutting internal splines on a mill.
- From: Lawrence London <lfljvenaura@gmail.com>
- To: machinist@lists.ibiblio.org
- Subject: [machinist] Tool design for cutting internal splines on a mill.
- Date: Tue, 29 Oct 2013 22:53:18 -0400
http://www.practicalmachinist.com/vb/general/tool-design-cutting-internal-splines-mill-274290/
Tool design for cutting internal splines on a mill. - Page 2
http://www.practicalmachinist.com/vb/general/tool-design-cutting-internal-splines-mill-274290/index2.html
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Tool design for cutting internal splines on a mill.
Hi all, I would like to cut some straight internal splines in a steel bushing. To adapt a crankshaft pulley from one engine to another that has a splined crankshaft. I have a mill with a rotary table, and a lathe but no dividing head. I thought to use the mill and the rotary table.
I made a cutter to chuck up in the mill and then lock the quill rotation with the brake, and manually stroke the quill and move the table to make the cuts.
So far I am doing OK, the tool is cutting, but I am wondering if there may be a better design for the cutter. This was a first attempt at a cutter, and the tip is not cutting exactly square, So I expect to have to make a new cutter
this is what I have for a cutter. It is home hardened with oil quench after being ground.
I need to cut 18 splines. The major diameter is 0.968", the minor diameter is 0.867" The spline width is pretty much 0.100". The bushing will be approx. 1.25" deep.
Does anybody have a picture of a cutter design I can look at so I can improve my next cutter?
thanks-
10-29-2013, 12:24 PM #2
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I don't know how you are fitting that down a hole that is ~1" ID?
Unless you are jamming it in endwise?
If indeed the tool is going in endwise, the geometry is wrong. Turn picture #2 over 180° and put the tool in a boring bar.
That would be about the correct presentation if the work is below the tool, though there is still kind of a weak edge.
Also, don't fool around hardening high carbon steel for an app like this. Just grind the end of a (hardened) HSS tool (lathe) bit and use it in a boring bar. Straight M2 HSS is better than cobalt steel, but up to maybe 5% is ok, if that is what is on hand. Cobalt will make the edge too brittle. (It's good for high speeds, which you will not be generating
)
This is about the presentation the end of your tool should have to the work. Only yours would be held in a boring bar for internal slotting. Sorry I don't have a better picture of the business end.
I'm assuming you don't have a surface grinder & perhaps spindex. But if so, it is easy to make endworking tools like this out of HSS sticks or rounds. Then when it dulls, just sharpen the end.
smt -
pic #2 is 90 deg off from how it fits in the vertical mill. there is plenty of room. I am not worth a dam at photo editing, or I would put some marks on the pic. I am using the quill to stroke the cutter vertically,
Thanks for the advice on hardening. The only tool steel I have available today is too small for this, so I am using mild steel at present and then hardening. my hardening process is crude but quick, and seems to work ok -
10-29-2013, 01:01 PM #4
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Did you grind that one with a chain saw?
Originally Posted by diesel-xj
Hi all, I would like to cut some straight internal splines in a steel bushing. To adapt a crankshaft pulley from one engine to another that has a splined crankshaft. I have a mill with a rotary table, and a lathe but no dividing head. I thought to use the mill and the rotary table.
I made a cutter to chuck up in the mill and then lock the quill rotation with the brake, and manually stroke the quill and move the table to make the cuts.
So far I am doing OK, the tool is cutting, but I am wondering if there may be a better design for the cutter. This was a first attempt at a cutter, and the tip is not cutting exactly square, So I expect to have to make a new cutter
this is what I have for a cutter. It is home hardened with oil quench after being ground.
I need to cut 18 splines. The major diameter is 0.968", the minor diameter is 0.867" The spline width is pretty much 0.100". The bushing will be approx. 1.25" deep.
Does anybody have a picture of a cutter design I can look at so I can improve my next cutter?
thanks
-
This is your problem... No way you can get mild hard enough with a "crude" hardening process.... Even harbor freight sells HSS. It's probably even close enough to "real" HSS to work decently. Originally Posted by diesel-xj
The only tool steel I have available today is too small for this, so I am using mild steel at present and then hardening. my hardening process is crude but quick, and seems to work ok
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Mild steel doesn't harden with ordinary processes. Thats why its called mild.
The good news is it looks like you have enough heat to silver braze. Use a piece of 3/4 mild steel round stock of sufficient length. Silver braze a piece of HSS on the end with sufficient overhang to grind your cutting edge. You can even rough the cutting edge before brazing, but I would finish grind after brazing. The tool bit could also be tig welded. Mig and stick are possibilities but usually the proper filler isn't at hand.
If you don't know how to braze, search this site. There is a large amount of information about brazing.
Don't try to make the cutting edge from carbide. It will chip.Casady Machine likes this. -
+1 on the mild steel, rather get tool steel, grind to shape and carry on, by the time you actually get the splines to size with the crank splines you'll be ready to change the crank pulley into a flying saucer, that is unless you have a lot more free time and patience than me
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Wow I guess a lot of people were not enjoying their lunch break. The cutter I had made is actually cutting pretty well, and quicker than you would think. once it got started. in a practice piece. jonwelden your comment was particularly not helpful. Didn't your moma teach you anything. Harbor freight is a 2+ hour round trip. I thought to re-task a drill bit, but again the cutter I made just now is cutting pretty well for me.
I was just looking for a picture or drawing of an example cutter to see if my angles were close or could be better -
10-29-2013, 02:53 PM #9
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the tool is not hard enough and it's edges are breaking down rapidly and giving poor results. braze something up with HSS or get some good HSS tool blanks.
oldbikerdude37 likes this. -
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here is a pic of the crankshaft that I need to fit the new pulley too. I understand about HSS steel. I guess I will re-grind a tool I already have, but it is square shank, I think am going to have holding issues with the set up I have and a square tool,
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Since you have a lathe, so make the shank round (rough grind it first to get it nearly there). Otherwise set up the same operation in the lathe. Originally Posted by diesel-xj
here is a pic of the crankshaft that I need to fit the new pulley too. I understand about HSS steel. I guess I will re-grind a tool I already have, but it is square shank, I think am going to have holding issues with the set up I have and a square tool,
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10-29-2013, 04:02 PM #13
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This is not the shape you are looking for, but maybe it will give some more ideas.
As can be seen from the bushing in this photo, I mill them so there is a couple degrees kick back. Then the tool only needs face ground. Though in your case there would be some side grinding. Due to the shape of your cut, it would not require specifically grinding side clearance, if the tool was kicked back.
If your mill or shaper & the tool set up is rigid, very little face angle is necessary. These tools used to be used in a mill-drill so they have a bit more rake, to compensate for deflection. Even then, if you put too much rake on, the tool will dig in (deflect into the work) so there is a compromise.
The tool you are building is a slotting or shaping tool, so it only needs somewhere between 2° & 4° clearance angles (side & top, or in your case "bottom"
). The face can be neutral, or slightly positive. If the face is
positive, it does change the profile, but you can presumably compensate
when grinding.
The tool should be about as big as will fit in the hole to avoid deflection, and the overhang should be very small and the bar short as possible. Again, I think you would be best served with a square HSS bit in a 3/4" shank or larger dia bar, held as short as possible in a collet.
But depending what you have to work with, you may get some other ideas here to add to the mix.
smt -
I wanted to do this in the lathe, but I don't have a way to divide out the splines . I thought it should be easier to divide it with the rotary table. I just found the tool bit I wanted to re-grind, I don't think there is enough left. I will either have to keep using what I have or get some more tool steel.
Brazing a tool tip on seems like a lot of work? Now I did think about trying to braze on a store bought cutter insert from a boring bar.
I just remembered I have a new solid boring bar I can re-grind that, and I can also use it in the boring head.
Which would be more accurate, to mount the cutter in the mill with a collet, and make the cut adjustments with the table, or put the cutter in a boring head and make the depth cut adjustments with the boring head. I know it will take 50 times as long to make the cut adjustments with the boring head.
I am still looking for a cutter example -
thanks Stephen Thomas, that is close to what I am looking for. If I want to do this today. the store bought boring bar I have is 1/2" shank. Do you think I can put that in a collet and make small cuts say .005" per stroke, that would be doable for me at 20 strokes per spline.
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I have cut 3/16" and 1/4 " internal keyways in blind holes with a tool made from a piece of Cold Rolled round stock that has an few degrees of angle in it, then silver soldered a HSS tool bit into the angled area, making sure to keep the tool bit parallel to the Cold Rolled. Put the tool in the spindle of a Bridgeport and start building some muscle in your arm. I can post a pic when I get out to the shop if you would like.
Big BGreg White likes this. -
thanks bigB, pics of the business end of the cutter is what I wanted to see. I think the boring bar re-grind will work. I can actually use the old worn out boring bar, not the new one. But I only want to grind that one once. I need this next cutter to be correct and work.
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Stephen Thomas, I looked at your pics more closely. Is your whole cutter set at an angle? it looks like there is no relief on what would be the back side or upper surface of your cutter. As your cutter is being pushed down in the quill making the cut. it is pushing the metal in front of it correct?
I have been grinding in some relief on the top/backside of my cutters. but if I am pushing the metal in front of the cutter, maybe I don't need that relief???? -
For this type of work you don't need to be ultra precise with the dividing. Wrap a piece of blue painter's tape (the type that removes easily) around the chuck and over overlap it a little, then use a knife blade to cut the tape to length. Remove the tape, that is the chuck's circumference. Measure the length and divide it by the number of divisions you need, scribe a line at each divided length with a sharp pencil then put it back on the chuck, the end should butt up against each other where you cut them and the lines represent each division. If you do it carefully this will be within a degree or two of the actual figure, and more than accurate enough for this job. For a pointer just use a dti on magnetic base, you don't actually use the dti, just use it as a pointer for the line. Lock the spindle at each position, but that will depend on the model lathe you have. If using gears to lock check that they lock at the preferred locations or you may have to rotate the spindle more or less, and that may throw the whole lot out to more than your tolerances. Originally Posted by diesel-xj
I wanted to do this in the lathe, but I don't have a way to divide out the splines .
Another method to index is to use a gear at the back of the spindle, however that normally requires a bit of fabrication. A handy thing to have if you have change gears just the same. Similarly many people drill indexing holes in their back plate, and mount a small indexing pin. I've not done this however as I just use one of my dividing heads or rotary tables, but I can see it would be handy at times. It's often a case of taking a somewhat longer route to the end goal, and building a fixture etc that can be used in subsequent jobs. -
I was just out practicing in some aluminum. I used a slit 3/4" bar to hold the tool in a collet, it worked well. My cutter design is still not great. I am going to try a die grinder to see if I can't get a more accurate tool. I would still like to see an example of a tool specifically for this application of manual plunge cutting in a vertical mill. My tool seems to need some relief on the sides.
The rotary table seems like it will work as well
who has some pictures of a spline cutting tool???
Reply
Tool design for cutting internal splines on a mill. - Page 2
http://www.practicalmachinist.com/vb/general/tool-design-cutting-internal-splines-mill-274290/index2.html
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You need to grind it like the ones smt showed, I would put around 3deg of relief on the non cutting sides and 7deg on the face. You have to balance the rake, too much and it digs in and not enough and it pushes back. Shaper tools are very similar to lathe tools, if you can grind a grooving tool you can grind the shaper tool almost the same.
I certainly wouldn't use a die grinder to shape that tool, dress your bench grinders wheel so it is smooth and straight and then hold on to it by hand and eyeball the angles.-
10-29-2013, 07:36 PM #22
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Originally Posted by diesel-xj
who has some pictures of a spline cutting tool???
Vertical Shaper Tools
Because the cutting motion on a vertical shaper is vertical instead of horizontal, the tools differ from those employed in the horizontal shaper. The cutting edge of slotter tools, as they are called, is on the end of the tool, so that it cuts when pushed endwise which puts the tool under compression. The cutting face that turns the shaving on the work is on the end. This is illustrated in Figure 43 where it can be seen that the horizontal axis 1-2 is parallel with the table and 3-4 the vertical axis. The clearance angle is designated by the line [3 to 7], and the rake angle by the line 2-6.
The usual rake angle that is ground on slotter tools for oridinary work is about 10 to 12 degrees, while the clearance angle is usally 4 to 5 degrees.
Shapers, Emanuele Stieri. Essential Books, NY. c.1942 -
thanks That helps a lot. in the diagram above is the whole tool made at the slots width? my slot width is only going to be .100" or close. I sort of had a tool with a tip that is the correct width, and then the rest gets fatter for support. I would still like to see a picture
I thought my electric die grinder might get me a bit more accuracy. my bench grinder is pretty clean, but still a bit bouncy.
thanks -
10-29-2013, 09:06 PM #24
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An example of an inexpensive, "traditional," 1/2" boring bar to use with the above method. Just cut down the shank and put in your milling collet.
- [machinist] Tool design for cutting internal splines on a mill., Lawrence London, 10/29/2013
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