Homemade broach slotting tool

[thehomeengineer]

Hi All
I had an interesting job come in to the workshop that needed to be broached/slotted.

These photos below show the finished component, setup and tool.


To cut the slots I decided to make a slotting tool from silver steel which was hardened and tempered. This was then attach to a mild steel tool holder.

The photos show the completed slotting tool and finished component.

To slot the component the quill of the milling machine is simply raised up and down without the spindle rotating. Taking very small/light cuts 0.02mm (0.001”) per/pass until the required depth is achieved.



To index the component it was placed into a indexing head and the mill spindle placed over centrally, each slot is then slotted to the required depth and the width of the tool maintains the width tolerance.



Finished slotted component cut to required tolerance +\- 0.05mm (0.002”)


With the component made from aluminium this did make the process a lot easier. However this method works very well on all materials but depending on the material to be cut the cut/pass my need to be reduced and cutting oil or coolant helps the cutting.
Hope this will be of interest and thank you for viewing

The Home Engineer

[Toolmaker51]

One extra kick for difficult materials adds 1 tooth, around half the feed distance higher, than entry tooth. Stagger reliefs and leading edges with a narrow cut off wheel; lessening tool load, narrower chips and promoting that extra drop of cutting fluid reaches area intended.
Examining a broach for a better description , also typical in larger forming broaches, hexes, rounds etc.

[DIYer]

Thanks thehomeengineer! We've added your Broach Slotting Tool to our Machining category,
as well as to your builder page: thehomeengineer's Homemade Tools. Your receipt:

Broach Slotting Tool by thehomeengineer

tags: broach

[mwmkravchenko]

One extra kick for difficult materials adds 1 tooth, around half the feed distance higher, than entry tooth. Stagger reliefs and leading edges with a narrow cut off wheel; lessening tool load, narrower chips and promoting that extra drop of cutting fluid reaches area intended.
Examining a broach for a better description , also typical in larger forming broaches, hexes, rounds etc.

A little quality time with an angle grinder and that could be any broach. I have skip tooth pipe threading male dies in the same line. I'm not a small man and I have a hard time turning a 1/8" normal pipe thread to a reasonably useful depth. The skip tooth version is fairly easy. I will remember this idea for sure.

[thehomeengineer]

Broach square holes with D-bit
This is a link to broaching square holes I posted a while back which works well on cutting/broaching accurate squares

[Toolmaker51]

A little quality time with an angle grinder and that could be any broach. I have skip tooth pipe threading male dies in the same line. I'm not a small man and I have a hard time turning a 1/8" normal pipe thread to a reasonably useful depth. The skip tooth version is fairly easy. I will remember this idea for sure.

Yup, skip tooth cutters in general, earn the extra expense involved. Broaches were probably first to benefit, then taps and endmills next. The narrow abrasive wheel is very much like a broach maker uses. Depending on the pitch, the cut more or less mimics relief on the cutter. Others look as merely ran it through, just alternating the line. I'd figure out means to regulate depth parallel to increased ramp of cutter teeth, not the spine.

Largest broach I've seen example of, used making Rambler auto engines, especially decking seats of main bearing caps. Inside that engine, biggest webs imaginable for a mere straight six, beefy to withstand force needed to broach the surface.

Thinking a 1-1/2" broach has 5 such cuts, not only staggered, but in a pattern, other than .200 skipped to one side in 20 something inches. That might induce deflection.

[Toolmaker51]

A little quality time with an angle grinder and that could be any broach. I have skip tooth pipe threading male dies in the same line. I'm not a small man and I have a hard time turning a 1/8" normal pipe thread to a reasonably useful depth. The skip tooth version is fairly easy. I will remember this idea for sure.

Occurred to me just now, a tap or die is essentially a skip toothed cutter. I looked up that variety pipe tap, carrying only a small portion of expected thread form.