Poor mans slotting head

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timo_gross

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Hello,

I am getting side tracked all the time :). Reading this in a gear cutting thread. .....

Hi All,
Now just the engine, still need to do the 1/16" key way in the drive gear, then heat treat the gears.
Cheers
Andrew

Results in fixing my poor mans slotting head. Replaced the not very successful dove tail with a 2nd hand linear rail.
Is it wasted time? Anyway sort of a fun project. As drive it has a 10:1 used gear motor.
K1600_P1000931.JPG

Now I have to remove the spindle head from the milling machine in order to mount the heavy thing. A better change over solution would be clever.

I cut some gear rack out of 6 mm brass stock. It behaves with the diy gear (right) and the plastic gear from scrapped printer.

K1600_P1000932.JPG K1600_P1000933.JPG

How to align a hole properly relative to the cutter is the challenge now. If anyone has a good tip it would be nice.
 

djc

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How to align a hole properly relative to the cutter is the challenge now.

I can only speak for slotting in a shaper, but it might give you some ideas.

The slotting bar in a shaper is round, with a square hole through it for the toolbit. I make a bush OD the size of the hole to be slotted, ID the diameter of the slotting bar. Push the part onto it, touch it against the means of clamping (vise, angle plate) and it is automatically aligned.

If your bar is square and vertical and looks to use a round tool bit, you could use a round bar with a perpendicular hole in it the size of the toolbit, clamped vertically.

The principle is to align the part with the cutting tool and then clamp it rather than trying to align the tool with the part after clamping.
 

timo_gross

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The principle is to align the part with the cutting tool and then clamp it rather than trying to align the tool with the part after clamping.
Hello, thank you for the reply. The vertical DIY thing and the shaper are probably quite similar, all I need to do is tilt my head 90° :).
My flimsy hobby mill is not as rigid, that I try to compensate with small cuts.
Trying to use some sort of alignment pin, or bush and let the work float before clamping is probably an efficient approach.
To use a round slotting bar with a separate tool bit is maybe difficult, because my bore in the gear is only 8 mm diameter, but when I grind the slotting tool out of 8 mm HSS bar instead of square I might use the upper part for alingment and the lower part for slotting. (made a draft, how I imagine the tool)
Then I just need a clamp adapter to install the bar.

Gretings Timo
 

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timo_gross

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I tried to make the tool, now next step is to try to fix it to the machine somehow.
Tool_experiment.JPG

Working on it.
 

timo_gross

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[QUOTE="djc, post: 378530, member: 181"

The principle is to align the part with the cutting tool and then clamp it rather than trying to align the tool with the part after clamping.
[/QUOTE]
Hello, yes it worked. Maybe this becomes the usual procedure.
I lowered the tool with the cylindrical part into the bore, then I clamped and zeroed the position. Adjust z-height and ... GO!. head_with_new_tool.JPG GTpulley.JPG
 

Drawfiler

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Why are you not using a push broach, they are not too expensive here in the uk, do a good job and your time is spent modelling not toolmaking!
 

timo_gross

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Why are you not using a push broach, they are not too expensive here in the uk, do a good job and your time is spent modelling not toolmaking!
Yes you caught me. Is toolmaking part of the hobby, or procrastination? Maybe both :), lots of tooling made, not so many models yet... .

Seriously: I was trying to find a push broach locally at first, but no one seems to use them here unless it is for mass production.
I do not have a press to push the push broach, would the lathe tail stock be good enough?

Greetings Timo
 

timo_gross

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Some home gunsmiths use a large, Bridgeport type mill quill to broach the mortise on single shot rifles etc. I suppose a smaller mill might work if the depth of cut was smaller.

It actually works fine now. Internal 2 mm keyways into 10 mm wide mild steel gears took about 90 seconds to setup and do the cut.
Depth of cut is in the range of 0.02 aka 1/1000" per stroke. I do not see much gain in trying to speed that up much further at the moment.
The HSS tool seems to be "happy with mild steel".
 

Drawfiler

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So the toolmaking paid off, I make quite a few gears with key ways and quickly found that using a slotting head rather slow and went for broaching, I also find the keyways are less likely to be tapered.
 

SmithDoor

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So the toolmaking paid off, I make quite a few gears with key ways and quickly found that using a slotting head rather slow and went for broaching, I also find the keyways are less likely to be tapered.
I keep thinking of using a crank and drill quill on the mill. Maybe using a low speed hand drill or a gear motor to supply the power.

Dave
 

dazz

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Hi
I made a simple tool that is held in the quill of a poor man's Taiwan milling machine.
 

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timo_gross

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So the toolmaking paid off, I make quite a few gears with key ways and quickly found that using a slotting head rather slow and went for broaching, I also find the keyways are less likely to be tapered.
Hello,

I just found out that I can now buy a 2 mm keyway broach without bushings for under 20 USD from the Aliexpress people. :oops:
When I checked a while ago I could not find smaller than 4 mm ones.

I make myself still believe it paid off.
For the fun of trying to make my own "working Model" of a slotting machine. Not made from castings, it is more the bar stock type though :cool: .
A taper is at least not "visible", if I measure precise enough .... it will for sure reveal a mess, so I better not measure. (but usable for now)
Because the tool has the same dimension as the bore, 8 mm in the slotting direction, it is possibly as stiff as it can be made. (unless I grind one from carbide and beef up the entire setup).
Tools are cheap; time for tool grinding not factored in. The HSS blanks do not break the bank at under 2 Pounds per piece, good to make two slotters.

I hope I can use the machine to make some other slotting jobs. Gear racks are already possible.
Square holes?

Hi
I made a simple tool that is held in the quill of a poor man's Taiwan milling machine.

How big is your tool? It is for sure very versatile, you can make a lot of different shaped cutters for it.

The machine on the fotos is originally from China (I guess), it lives in Taiwan, the Japanese gear motor is a 0.4 kW 4-pole running between nothing and 90Hz.
Used cutting parameters were 230 strokes per Minute and infeed of 2mm/min.

I guess hand cranking can become boring. I also think that the relative high speed gives it some momentum and that probably helps with the cut.

Greetings Timo
 
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dazz

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Hello,

I just found out that I can now buy a 2 mm keyway broach without bushings for under 20 USD from the Aliexpress people. :oops:
When I checked a while ago I could not find smaller than 4 mm ones.

I make myself still believe it paid off.
For the fun of trying to make my own "working Model" of a slotting machine. Not made from castings, it is more the bar stock type though :cool: .
A taper is at least not "visible", if I measure precise enough .... it will for sure reveal a mess, so I better not measure. (but usable for now)
Because the tool has the same dimension as the bore, 8 mm in the slotting direction, it is possibly as stiff as it can be made. (unless I grind one from carbide and beef up the entire setup).
Tools are cheap; time for tool grinding not factored in. The HSS blanks do not break the bank at under 2 Pounds per piece, good to make two slotters.

I hope I can use the machine to make some other slotting jobs. Gear racks are already possible.
Square holes?



How big is your tool? It is for sure very versatile, you can make a lot of different shaped cutters for it.

The machine on the fotos is originally from China (I guess), it lives in Taiwan, the Japanese gear motor is a 0.4 kW 4-pole running between nothing and 90Hz.
Used cutting parameters were 230 strokes per Minute and infeed of 2mm/min.

I guess hand cranking can become boring. I also think that the relative high speed gives it some momentum and that probably helps with the cut.

Greetings Timo
It is as big as you need.
Since making that tool, I now have a Deckel clone milling machine with a slotter.
It works the same except that it is now motor driven
 

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wazrus

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Broaches. I do have few, they are pricey little items and the market for shorter broaches isn't all that good. So I've made my own, using pieces of simple round steel to suit the job and the cutter bars are about 200mm long, machined with a taper on the back, to allow .015" cuts per pass. The round steel has a very deep keyway machined, of a length to allow the cutter bar to seat, The cutter bar is simply packed up, with each successive cut, to allow a 0.15" cut per pass. There is a small brass thrust 'plug' used at the ends of the bar, in the slot. the cutter bars are fairly simply made from HSS bar of, say 3/16"or 1/8" thickness or whatever, by 1/2". The teeth are cut using a narrow wheel in an angle grinder mounted on a fixture and the bar is moved back-and-forth for each tooth. Side clearance I've found to be unneccessary; the cutters are quite parallel. The tooth form is not unlike that used by circular timber saws, without the 'set'. The broaches are pushed through the work with a 3T mandrel press. I've cut dozens of keyways in most materials with complete success and the broach cutters are quite easily sharpened. I've never broken one of those broaches. I do have a shaper and 'my' broaches have pretty much replaced the shaped process for keyways.
 

dazz

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Hi
This is the latest design for a slotter tool. This is designed to make a blind round hole into a square one.
The hole is too small to fit a tool holder so the round bit will be cut square to fit in the hole and cut it into a square.

The alternative is to braze a piece of HSS into a slot as shown in the 2nd tool holder.
None of these can be purchased, but they are easy to make.
 

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timo_gross

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Hi
This is the latest design for a slotter tool. This is designed to make a blind round hole into a square one.
The hole is too small to fit a tool holder so the round bit will be cut square to fit in the hole and cut it into a square.

The alternative is to braze a piece of HSS into a slot as shown in the 2nd tool holder.
None of these can be purchased, but they are easy to make.
If you square up the blind hole, is the cutter simply going up and down? Were are the chips ending up?
 

dazz

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Hi
I will bore a groove in the base of the hole to provide chip and tool clearance.
Bad things would happen if the tool just stopped at the end of the hole.
 

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Ozwes007

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Blind hole keyways are usually terminated with a hole slightly over the key size. This maintains the structural integrity of the unit being keyed. Undercutting can lead to failure at the undercut.
 

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