Thread: More (mad?) Mars Mods

Hi Ewan,

Looking good so fair.
Got a picture of the where the single tooth clutch is fitted to the lathe?(its fixed 1:1 to the spindle right?)

Stuart

Originally Posted by Stustoys

Hi Ewan,

Looking good so fair.
Got a picture of the where the single tooth clutch is fitted to the lathe?(its fixed 1:1 to the spindle right?)YES

Stuart

The last pics shows it in place, but doesn't really show where that is.....

Its under the main spindle, the drive comes down through the tumble reverse, and then onto a hollow shaft (that runs in the bronze bearing to the left of the last pic). The LH bevel gear is on this shaft, and the shaft the clutch is on runs in the hollow shaft and back out to the stud gear. Clear as mud?

Ew

I spent some time today sweating (although not as much as you SA guys i bet!) and whilst doing that i also cut 2 of the gears. It all went remarkably well, that was after i made a new arbor for the gear cutter (as my older one was not long enough) and a mandrel to mount the gears on. I cat them in 2 goes not 3, didn't really see the point in gashing out the middle only to trim either side off afterwards.

They mesh well, but i don't seem to have much space left for my clutch blocks, i was thinking even just putting a small SHCS in for the lugs on the gears and an MS block on the clutch "slider" itself. I could probably make the gears 2 teeth bigger before i run out of space, that would get me some more room. Or make them thinner....

Cheers,
Ew

Edit, the Quick Knurler arrived today, but i was having too much fun with the gears to take any pics. However i just noticed the corner of the box made it into the 3rd pic. Hows that for a teaser.

Nice work, you be over hear cutting after all this.

Dave

Originally Posted by Ueee

Why mad? Well i'm seriously wondering why i need 4 lathes, so once either the Rivett or the LeBlond is finished i will probably sell the Mars. But then its almost always about the journey for me and not necessarily the destination....

I used to own 5 lathes, now I'm down to 4 and seriously reducing that to 3. In fact 2 would do if I didn't have the 3rd one at my Sydney house.

A smallish lathe capable of high speeds and a more 'delicate' feel plus a much bigger lathe is a damn good combination. In my case, a Chipmaster 5" x 20" and a Monarch CY 18" x 54". I so rarely use the 28" swing machine that it really doesn't justify the floor space it occupies.

PDW

Originally Posted by Ueee

I spent some time today sweating (although not as much as you SA guys i bet!) and whilst doing that i also cut 2 of the gears. It all went remarkably well, that was after i made a new arbor for the gear cutter (as my older one was not long enough) and a mandrel to mount the gears on. I cat them in 2 goes not 3, didn't really see the point in gashing out the middle only to trim either side off afterwards.

They mesh well, but i don't seem to have much space left for my clutch blocks, i was thinking even just putting a small SHCS in for the lugs on the gears and an MS block on the clutch "slider" itself. I could probably make the gears 2 teeth bigger before i run out of space, that would get me some more room. Or make them thinner....

Cheers,
Ew

Edit, the Quick Knurler arrived today, but i was having too much fun with the gears to take any pics. However i just noticed the corner of the box made it into the 3rd pic. Hows that for a teaser.

Hi Ewan,
the teeth on the bevel gears look tapered. Just wondering if you offset the gear blank from the centreline to compensate and give correct tooth form. I think the blank has to be rotated as well a proportionate amount. Running on memory here so I may be talking through my proverbial.

Phil

Your dead right Phil. The gear is moved 1/2 the chordal thickness off center and the blank rotated 1/4 of the indexing amount, then the first cut is made (of course there is no need to rotate the blank for the first cut). Then the blank is moved back to center and then 1/2 the chordal thickness the other way and is then rotated 1/2 the indexing amount (1/4 back to center and 1/4 the other way).
To be honest they are pretty easy to cut, far easier than proper non parallel depth bevel gears. The maths on working out the blank diameters and pcds is the tricky bit.

Cutting away at 4" a minute they don't take long to cut either.

Dave to be honest, rather saidly I kind of enjoy cutting gears.....
Cheers,
Ew

Nice work Ewan, good to see that dividing head getting a workout. I will be interested to see how the dog clutch works.


Regards
Ray

Originally Posted by Ueee

Your dead right Phil. The gear is moved 1/2 the chordal thickness off center and the blank rotated 1/4 of the indexing amount, then the first cut is made (of course there is no need to rotate the blank for the first cut). Then the blank is moved back to center and then 1/2 the chordal thickness the other way and is then rotated 1/2 the indexing amount (1/4 back to center and 1/4 the other way).
To be honest they are pretty easy to cut, far easier than proper non parallel depth bevel gears. The maths on working out the blank diameters and pcds is the tricky bit.

Cutting away at 4" a minute they don't take long to cut either.

Dave to be honest, rather saidly I kind of enjoy cutting gears.....
Cheers,
Ew

Hi Ew,
many thanks for making my head explode...again
I vaguely remembered there was something annoying about bevel gears so I have now dragged an old 11th edition of the Machinery's Handbook out and started some light reading.
I have to cut 6 sets of bevel gears at work soon, (hence the dividing head) so I may be picking your brains as the 'light' reading involves 45 pages of very small writing which means I also have to locate my glasses
It sucks how this all made sense when I was an apprentice but now it makes my head explode.
I shouldn't have to pick your brains too much as it is starting to come back to me but I am confident that between you and Michael G, I wont have a problem.

Phil

Phil do you have Ivan Law's book? If not I can help. May be more digestible than MH.

Hi Bryan,
not only do I not have a copy, I'm not sure I have even heard of it before

Phil

As I was walking past my old camel back drill today , I looked at the bevel gears that drive the spindle - reminded me of this thread

The gear teeth are tapered somewhat , just like Ewan has done

Mike

Hmmm, I might have a closer look at the ones I have to replace.

Phil

Hey Ewan, Phil,

Did Phil get a copy of 17 yet? Would you believe someone ordered a copy and then thought it would be a good idea to check if he already had a copy............Some may say that was the wrong order and I would tend to agree with them.

Something looks wrong with that gear to me.... but then I wouldnt have a clue so I've been waiting to see it finished!

BTW Its not a bench

Stuart