Cutting a slot at a weird angle and size.

[Flyinfool]

Project I am working on requires a slot be cut in the side of the part at a 78.75° angle to the center line.

The slot needs to be .204 wide and .437 deep.

Of course there is no surface square or even an even degree from this slot to set up on.

The part will already be on the rotary table for other operations so my thought is to use a 4" x .125 slitting saw to make the slot from the side. Simple to turn the table to the desired angle. It would be very difficult to fixture this straight up to make the cut with an end mill. I would probably need to buy a sine vise and a set of gauge blocks to set it up for the end mill.

The plan was to make a first cut on center and then shift up and down for the final cuts to size. The part I am not sure of since the slitting saw will only be cutting .0935 of its .125 width will it try to deflect away from the cut. It is a side tooth type of slitting saw so I think that will help it to stay on line.

OR

Would I be better off taking the first cut on location and then just one second cut that will be cutting 0.079. I am not sure if the heavier less than full width cut will try harder to deflect or deflect less?

If I go slow enough will the side cutting teeth clean up any deflection???

I thought about using a 1.500 dia x .1875 wide Woodruff key cutter and do this in 2 passes, I think this cutter will be stiff enough to not deflect, But I do not have one of these and they are very expensive, I do have the 4" x .125 saw.

 

[Chipper5783]

Use a mill with a tilting table (Maho 600, or Deckel FP1). There likely are other offerings (that European style was much copied). For a conventional knee mill, there are a number of tilt vise options (depends on the part configuration).

Maho "Universal Tool Milling, Drilling and Boring Machine" - MH600

There hasn’t been much activity on this forum re the “European Style” mills. Sam has encouraged me with the pictures of his “new” FP1, so I am sharing information on my machine. I have seen them variously referred to as “Toolroom” or “Diesinking” machines. The works original documentation...

www.hobby-machinist.com

 

[talvare]

I think your concern about the slitting saw deflecting is justified. You could try on a scrap piece to see if it works. Another possibility is using one of the old style boring bars that uses HSS lathe tools. With this you could grind the tool bit to cut the exact width you need. If you don't have one of those boring bars, they're not difficult to make. Here's an example of what I'm talking about:

Precise Double End Boring Bar, 1/2” Bar Diameter - 1015-0502

Offering a huge selection of industrial tool sales online. Find over 100,000 metalworking products, precision measuring tools, power tools & accessories.

www.penntoolco.com

Ted

 

[Provincial]

If you have a boring head for the mill, you should consider making an adapter to hold a square tool bit. I made one thirty years ago to bore out a bearing pocket and put a snap ring groove in it. I made the slot for the tool bit 5/16" because that is the tool bit I needed for the job. Notice the offset of the slot to put the cutting edge on center. The round "nut" fits in the horizontal hole in the head, and acts as a nut for the two mounting bolts. The guide bushings are pressed into counterbores made with a 1/2" end mill and they hold the adapter true to the body of the tool.

You could take a HSS square bit and grind it to the width of your slot, then cut the slot like a fly cutter.

 

[mmcmdl]

As stated above , make a little bar to hold a 1/4" HSS bit . Grind it to size and hold it in a collet . Really no need for a boring head .

 

[Flyinfool]

Glad I asked, these are all some options that I had not thought of. Time for some thinking and experimenting (a VERY dangerous combination for me).

 

[GT-6 Racer]

Use a mill with a tilting table (Maho 600, or Deckel FP1). There likely are other offerings (that European style was much copied). For a conventional knee mill, there are a number of tilt vise options (depends on the part configuration).

Maho "Universal Tool Milling, Drilling and Boring Machine" - MH600

There hasn’t been much activity on this forum re the “European Style” mills. Sam has encouraged me with the pictures of his “new” FP1, so I am sharing information on my machine. I have seen them variously referred to as “Toolroom” or “Diesinking” machines. The works original documentation...

www.hobby-machinist.com

Love my Deckel FP3 with a universal table For easy angles.

but aside from that, consider the grinding vise in a mill vise trick. Set angle with a sine bar So you can mill the slot with an end mill.

 

[Flyinfool]

I was sure enough that the saw will not work that I orderd a bar of 1.500 dia of steel and the 1/4 lathe bits to make a tool.

After some thought and experimenting I did try cutting a slot in some scrap using the slitting saw.

The saw was not what I remembered. it is actually a 3" dia x .125 thick with 1.000 bore side cutting slitting saw. I think had it been a 4" dia that it would have deflected. there was some deflection with the 3". the arbor has a 1.500 OD.

I made the 0.204 wide cut by first making a cut on center. then offsetting to each side by 0.0395.
The side cutting of the blade was definitely doing its thing. Once the full depth broke through at the end of the cut I could still hear contact and se aluminum dust coming out of the cut until the full blade had passed thru. So the sides of the slot were still cleaning up some,

The result came out to .2052 wide at the top of the slot and 0.2047 at the bottom of the slot. 1/4 of one thou taper per side I will take any and every day.

Thank you all for the suggestions they were very helpful for me to get my head wrapped around this one.

In case you are interested here is the thread for the project that this is part of.

Converting my old pneumatic retracts to electric.

I have an old turbine powered jet with retractable landing gear. This jet is now about 20 years old. The old pneumatic system is getting old and tired. Between age attacking the seals and just plain wear they just do not work well any more. There is also the fear that I always have while filling...

www.hobby-machinist.com