What are you machining?

[Richiew]

Bit of a repeat, but another keyway broach bush.

It's 9/16" diameter with a 3/16" wide slot. The slot accepts an "A" type broach and will cut a 1/8" keyway. The bush cuts keyways for Southbend/Boxford lathe gears.

The important thing is to accurately find centre for the slot otherwise the keyway will be wonky.

A Doubleboost style wiggler was used to accurately find the edge of the bar, the centre was then located using the DRO.

I've measured up the remaining width either side of the slot as best as can be done with a set of Aldi calipers and the two sides are within 0.05mm of each other so I'm pretty happy.

I have another bush to make for a 5mm keyway broach soon. Waiting for it to turn up so I can measure for the slot depth before milling. It has been turned already.

These are great little jobs for practising basic machining operations.

Incidentally, tonight I found my missing 20 tooth lathe gear that I made a hash of trying to make. It was hiding behind a larger gear on the lathe gear train.

 

[Richiew]

Just looked again at my photos. It is clearly a "B" broach not an "A".

Talking rubbish. Again.

 

[Tigman]

I've machined some slots in 100 x 50 PFC , easy with the bridgeport !

 

[Barking Mat]

Bit of a repeat, but another keyway broach bush.

It's 9/16" diameter with a 3/16" wide slot. The slot accepts an "A" type broach and will cut a 1/8" keyway. The bush cuts keyways for Southbend/Boxford lathe gears.

The important thing is to accurately find centre for the slot otherwise the keyway will be wonky.

A Doubleboost style wiggler was used to accurately find the edge of the bar, the centre was then located using the DRO.

I've measured up the remaining width either side of the slot as best as can be done with a set of Aldi calipers and the two sides are within 0.05mm of each other so I'm pretty happy.

I have another bush to make for a 5mm keyway broach soon. Waiting for it to turn up so I can measure for the slot depth before milling. It has been turned already.

These are great little jobs for practising basic machining operations.

Incidentally, tonight I found my missing 20 tooth lathe gear that I made a hash of trying to make. It was hiding behind a larger gear on the lathe gear train.

View attachment 350546

View attachment 350547

View attachment 350548

View attachment 350549

Why so deep ?

Never seen a keyway that deep.

 

[Richiew]

Why so deep ?

Never seen a keyway that deep.

It's just because the bore/shaft is relatively small. It's only 9/16" which is very much at the small end of things.

From memory, the broach was roughly nine and half mm deep.

On a larger bore, the slot wouldn't look as extreme.

They can't make the broaches too small and delicate as they would likely snap.

 

[Richiew]

This is it posed with a completed gear. There's a missing spacer shim that goes in the back to push the teeth into the cut on the second pass, this is why it looks a bit recessed here. The teeth protrude more towards the top as well to give a progressive cut.

 

[Richiew]

Here's a couple of better pictures. I have installed the shim and the broach is driven up to the top tooth. We can see it is pretty much exactly where it should be.

Curiosity got the better of me so I took a few measurements.
Shim thickness 0.85mm
Slot depth 9.50mm

Tooth heights. The teeth have a bit of angle on them so it hard to get an exact height with a micrometer and I wasn't hanging about when taking measurements.

9.55
9.65
9.70
9.83
9.92
10.00
10.12
10.18
10.32
10.41
10.45
10.52
10.55

This is an average of 0.077mm cut depth per tooth so my slot depth should have been about 9.48mm to obtain the average cut with the first tooth
Close enough I reckon.

 

[Anguz]

What are you driving the broach in with? Bfh?

 

[Richiew]

I have a hydraulic press. It is rated at 20 tonne. But the pressure gauge needle barely rises off its zero stop when cutting as the teeth take so little material.

I think an arbor press is the correct tool to use.

 

[Richiew]

This is quite a good resource. The table shows a 3mm broach takes only 295kg (650lbs) of pressure to cut.

https://www.suncoasttools.com/crm/pdf/PILOTMETKEYWAY.pdf

 

[Tigman]

Today I had a go with a little fly cutter ! , this will end up as t nuts !

 

[striker]

A few parts for my 3 speed coaster hub conversion for my old fixed wheel bike.
A cable stop.
A head tube extender.
A gear lever boss.

All to be Tig brazed on when my rods come!

 

[Tigman]

T nuts coming along

 

[Munkul]

Started roughing out my fly cutter from a bit of scrap 6" round... It didn't look like this when I started!
It had keyways and flats and holes in this end, so the interrupted cuts were a bit of a pain, having to slow down for them. Now I'm passed them and can motor on at 4mm DOC and 0.3mm/rev.
I need a 32mm shank, so plenty to go... although half wondering about making it arbor mounted rather than shanked... the slot will be a royal pain to set up for milling.
It cuts nicely, it's not hard enough to be en24 or en19, but too tough to be en8, so maybe it's en16.

 

[Rrobson]

May be of interest to some, a little unconventional line boring to renew a seal location in situ. Been in the planning for nearly a year so I was relieved it did the job. Dimensionally accurate to a thou and to correct surface finish.
Fasteners are 2” for reference and the machined face is around 60” deep.

 

[Tigman]

Puts my t- nuts to shame !

 

[Brad93]

May be of interest to some, a little unconventional line boring to renew a seal location in situ. Been in the planning for nearly a year so I was relieved it did the job. Dimensionally accurate to a thou and to correct surface finish.
Fasteners are 2” for reference and the machined face is around 60” deep.

View attachment 353614

What make boring kit did you use?

 

[Maker]

May be of interest to some, a little unconventional line boring to renew a seal location in situ. Been in the planning for nearly a year so I was relieved it did the job. Dimensionally accurate to a thou and to correct surface finish.
Fasteners are 2” for reference and the machined face is around 60” deep.

View attachment 353614

That's an impressive bit of kit! Can you say what the part being machined is?

 

[Rrobson]

What make boring kit did you use?

It’s a mirage lb90. I don’t believe this model is available any more, but looking at the brochure online it seems to have been replaced with the lb100 which is basically the same machine according to the specs.
Got quite a bit of mirage gear, top quality stuff.

That's an impressive bit of kit! Can you say what the part being machined is?

It’s a combined stop and control valve. IP steam system in a power station

 

[Tigman]

T - nut !