I know there are a lot of ways to do this but because of the precision needed is there a best way.
Because the table height varies across my table from 0 in the center to +/- 0.02mm across the Y max-min. Because of this the tool setter is only accurate in a couple positions. This is the reason my tool setter is as close to my A-axis center as possible. So to measure gear cutters and slitting saws I do a Z-only Move and set tool length on the Y-axis above and below the tool setter and average the 2 measurements, then rotate the saw 90 degrees and average the 2 measurements again. While this seems to work the first cut is always a throw away because the flex in the saw throws off the first cut. So is there a better way?
Gear cutters are just a nightmare. Usually I probe the stock center then eyeball it and cut a slit in the end of the stock. Rotate the stock 180 and use a sharpie on the stock. Then make another cut and see if it’s centered. Then repeat for half an hour.
It’ll be difficult to predict flex in a saw, but if you’re getting flex in a cut, that cut isn’t going to be straight either and will probably end up in the breakage situation you had in another thread.
If I want to center a gear cutter with scratches, I don’t rotate 180, I rotate 60 or 270 or some other angle so there are 3 un-parallel lines and then correct for the center spot, but instead I’d try probe the tool, run an indicator over it or use an electronic squeaker to find the center point and record that. You only ever need to run it centered on the A-axis, right?
No, but if I can center it I can easily adjust. Sometimes I cut watch escape wheels with eccentric geometries requiring multiple cutters for a single tooth profile.
I understand your method, the 3 lines will converge and that shows you where to adjust based on a known center point. Could work. That way seems easier to calculate the adjustment because of the ability to measure to center.
I will try it but the gear modules I am cutting are 0.00445” so it’s hard to see.
I am using the standard tormach probe but I think I am up against its limits. Trying some small renishaw probe tips and hopefully I can get squeeze out some more resolution.
It might be worth your time to do a little rework on the slitting saw arbor. If you have a holder to dedicate to the arbor I would set that up and remove the saw and clamp screw. I’d then face the arbors saw mounting surface with a lathe tool in the vice. With the same setup I’d install a saw and the clamp assembly and face the bolt in the same way. You will have a saw and bolt head that is perpendicular to your spindle. You can then touch off with the arbor and comp the bolt, washer and 1/2 your slitting saw width for center line.
Can you run the saw across the face of a cylinder and measure either side of the cut?
Kind like finding dead center on a lathe tool. Might have to indicate the cylinder to make sure it’s true.
I’d jog the same increment every time coming down. If you don’t already.
That arbor in a hydraulic chuck is almost perfect. The runout is 0.0002mm axial and 0 wobble that I can measure on the cutting edge. I’m not messing with that. Was thinking of using a ring gauge on top of the tool setter. Then subtracting the gauge height. I just hate adding things between measured surfaces.
I dont have a on machine tool setter so I use the offline tool height setter for all tools.
arbor saws I measure the saw bottom surface then measure the saw thickness and subtract from height.
Gear cutters I do the same and measure the top surface while in holder then measure the cutter and subtract 1/2 the thickness to get gear cutter center line. I also verify the cutter is in fact on center.
Then I setup cam operations based on how the tool offset was measured and how tool is orientated to the material and the cut to be made.
Never thought about how I would do it with a online on table tool setter. Betting i would go old school and do it offline like I do now.
yellow lines display the arbor saw tool path with arc entry and exit shown in pic below.
I set the bottom of the part “red arrow” to match up with the top of the arbor saw surface that i set as height.
Like all cam ops and tools there is often dozens of strategies to setup and get same results and I will vary the way i setup tool heights based on the least problematic cam setup.
For arbor saw cuts in 4th axis setups I often lack a true or trusted surface to set the tool path with.
In Sprutcam I set the tool path to center of desired cut and setup arbor saw height at center of saw by measuring height the subtracting half the thickness and using that as tool height.
Pic below shows 4 arcing arbor tool paths in blue using center of one feature, Then multiply tool path by whatever is required in this case 4.
I think it sounds like you have some things to try from what the others have said, but I would add that I agree you are likely up against the repeatability and accuracy of the ETS unit and system as a whole. Looking at your photo, and working at a company that manufactures gear machines and cutting tools, I can also say that we would grind the involute geometry datumed on bore and mount faces, but that the top and bottom flat surfaces of each “block” would not be held tightly.
My solution and recommendation would either be to follow Bruce K’s idea, or skip ETS and mount a micron resolution “Last Word style” test indicator to the table and try to check the top and bottom flank of the involute, then find center. The probe would obviously need to be something like a .2 or .1mm diameter sphere.
My last comment would be to confirm (and account for) if the cutter has “set” - meaning every other tooth cuts the opposite flank. This can sometimes be done when full engagement of the entire involute would generate too large a cutting force.
That saw looks a bit coarse for that part.
MSC Industrial has a 1in. X .020in thick x 64 tooth blade. Might have to cut a little slower.
But if you’re happy that’s all that counts.
