HSS Tool geometry for shaping /slotting head on a mill.

[Flynth]

I've recently managed to adapt a shaping/slotting head to my horizontal milling machine, but I know nothing about grinding tools for it.

There is some info online about shaping tools for shapers. This is different. A shaping/slotting head has no clapper box. Just a tool holder that holds a square tool vertically. The working motion is vertical too.

If anyone knows of books or articles about tool geometry for such slotting/shaping please point me in the right direction.

I thought to do a quick test by trying to square a quarter inch round hole. I took a 3x10 mm HSS parting blank and I cut a 3x4 mm(0.120x0.160in) 15mm long (0.6in) long profile on the end. I ground 2 degree clearances on all 4 sides and I ground 3 degrees rake on the face.

This tool sort of worked, but it flexed a lot. Probably I should've made it bigger (as big as it could fit in the hole).

I'm mostly interested in using the shaping head to square holes in diy tool holders and boring bars. Also to cut an odd inside spline. I would live if there was some old book available online that talked about using such a shaping head.

 

[benmychree]

The clearances you used are about right, too much clearance, and the tools will hog in and likely break. One should only do the side and front clearance for a short distance from the cutting end of the tool and continue with straight clearance for the length of cut to keep the shank of the tool as stiff as possible. I have a shaping head for my B&S mill and also a Pratt & Whitney slotter (vertical shaper), it has a clapper box unlike the Milling machine's attachment. The cutters are about as rare as the proverbial hen's teeth.

 

[Flynth]

The clearances you used are about right, too much clearance, and the tools will hog in and likely break. One should only do the side and front clearance for a short distance from the cutting end of the tool and continue with straight clearance for the length of cut to keep the shank of the tool as stiff as possible. I have a shaping head for my B&S mill and also a Pratt & Whitney slotter (vertical shaper), it has a clapper box unlike the Milling machine's attachment. The cutters are about as rare as the proverbial hen's teeth.

Thank you. Good tip on clearances being straight. This will improve tool stiffness a lot.

Unfortunately, it seems written materials about those attachments are also extremely rare. I managed to find some old marketing materials, but no info on for example lubrication.

My slotting/shaping head has three places one could lubricate it. One is obvious - ball retention oilers for the drive shaft. Second - sort of obvious. It's a reservoir with some fabric string that makes way oil slowly drip through the box ways. The third however... Is a mystery.

There is a large access hole on top and a short piece of pipe covered by a spring loaded "hat". It looks like one is supposed to lift that hat ocassionally and squirt some oil in there. However when I did that the oil just dripped to the bottom. So I thought perhaps one is supposed to fill it with a bit of oil that will splash lubricate the insides and the big access hole, other than for setting the stroke, is for drainage.

Bad decision, on the first stroke up, when the ram lifted the oil I put inside drained to the bottom (thankfully I had a container handy). The mechanism is only closed by the ram on the front. So there is no way there can be liquid oil in there. So grease maybe? I have no idea.

There is a bearing in there that looks like it is covered in gunk. I think it really should get some lubrication, but I'm not sure how to deliver it. Before I started messing with this attachment I noticed remnants of very dark old oxidised oil in there.

So how do you(and others) lubricate their slotting attachments?

 

[benmychree]

About all mine has is the way lube point and one for the drive shaft and crank pin and the pin that drives the ram, given how little work is done with them, little lube is necessary.

 

[ErichKeane]

I don't have a shaping heat, but I have a shaper. One thing I keep in mind is to remember that the shaper bit can act like a 'shovel' and pull the material out of the vise. Its like a fly-cutter, only worse! To prevent that I end up ONLY cutting rake in the 'narrow' direction, and none/little in the 'long' direction (that is, only rake left to right/right to left, not bottom to top). You still need clearance angles on the bottom/sides though.

This ends up not being a problem for finish, because you're typically cutting on the 'leading' edge, not the 'bottom' anyway.

Note that one really cool version of the tool is a 'shear' tool for fantastic finishes, but only with small cuts. You keep the bottom 'flat' on the work (but remove the bottom 'points'), and make the leading edge 'further away' from the cut. It works like a shear tool on a lathe. I think Abom has some videos about trying to perfect it.

EDIT: Above is specific to the 'shaper' part of shaper/slotter For slotting I use similar tools, but don't do that enough to comment.

 

[benmychree]

One thing that can be done to lessen the tendency for the shaper tool to dig in and knock the work out of the vise is to use a shaper tool holder that can be reversed to locate the tool point closer to the pivot point of the clapper box, as the old classic "goose neck" tool, this also lessens the tendency to chatter, causing poor finishes. These holders are not so easy to find nowadays, but a similar holder could be made without too much work. I never had too much luck with shear tools on a shaper or planer, although I did fairly well with a tool with minimal front clearance and a generous amount of back rake, ground straight across the width of the tool and a slight radius on the leading and following edges of the flat bottom. Shear tools have a tendency to rock the tool around under cutting forces and any slack/wear in the clapper box can be a problem.

 

[Flynth]

Thank you for describing your experiences

I decided to make a couple of tool holders first. Then I'll experiment some more.

One thing to note is that my slotting head has no clapper box. The tool is mounted solidly (so only manual feeding is allowed I think).

I found some information on vintagemachinery.org website. There is a document titled "Milling practice series book 2" with a subtitle of "Milling machine and its attachments" and in there there is a little bit about slotting heads. Especially useful is information about how much to feed manually per stroke depending on the tool bit size. In general they recommend from 2 thou from small tools up to 10 thou for very rigid ones.

 

[benmychree]

My slotting head also has no clapper box, I just feed it as the tool comes clear of the cut on the return stroke. I thonk a couple of thou feed is about right for smaller tools, I think 10 thou might be a bit much, depending on the tool and feed direction.