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tumbler reverse
- Thread starter savarin
- Start date
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- Aug 22, 2012
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- Joined
- Aug 22, 2012
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As a 40 tooth gear is over $50 dollars and I'm a cheapskate I guess I will have to make one.
Hmm, bit of a project for a newbie but we all have to start somewhere.
Made the mandrel for the bit today, drilled and tapped into the end for a fixing bolt, drilled and filed a square hole across the bar.
Ground a bit of HSS into the closest I could estimate the gear profile required and stuck it in the bar.
Took a test cut on a short length of 3/8" plate clamped in the tool post.
by inking the teeth of a gear and rolling it along the edge of the plate I arrived at some semblance of a bunch of indexing marks.
Set the cutter on the mark, turned on and advanced the cross slide until what I thought was sufficient depth and cut a tooth recess.
Advanced the carriage to the next mark and cut again until I had approx 6 teeth cut.
They looked good, one tooth was a tad bigger than the rest but more importantly the gear rolled along the teeth meshing ok as far as I could determine..
Now I have to throw a height adjustment and indexing wheel together and have a real go.
I've seen one made from a couple of bits of heavy angle iron but cant find it now.
No worries I reckon I can nut it out.
Hmm, bit of a project for a newbie but we all have to start somewhere.
Made the mandrel for the bit today, drilled and tapped into the end for a fixing bolt, drilled and filed a square hole across the bar.
Ground a bit of HSS into the closest I could estimate the gear profile required and stuck it in the bar.
Took a test cut on a short length of 3/8" plate clamped in the tool post.
by inking the teeth of a gear and rolling it along the edge of the plate I arrived at some semblance of a bunch of indexing marks.
Set the cutter on the mark, turned on and advanced the cross slide until what I thought was sufficient depth and cut a tooth recess.
Advanced the carriage to the next mark and cut again until I had approx 6 teeth cut.
They looked good, one tooth was a tad bigger than the rest but more importantly the gear rolled along the teeth meshing ok as far as I could determine..
Now I have to throw a height adjustment and indexing wheel together and have a real go.
I've seen one made from a couple of bits of heavy angle iron but cant find it now.
No worries I reckon I can nut it out.
- Joined
- Aug 22, 2012
- Messages
- 4,292
It seems that my quest for a reverse tumbler and my stinginess preventing me from purchasing the requisite 40T gear is leading me into deeper territory.
I decided to make a small vertical slide to help in cutting the gear blank.
I had a small topslide casting already made for the Gingery lathe so thought I may as well use that as a starting point.
Everything else must come from the scrap bin (remember I'm stingy)
I cant produce engineering drawings and cant really read them either so I tend to work out my projects in an old 3d modeling/animation program to get it clear in my head and came up with this. It does mean I can check out clearances and fits before I cut anything as I can read the measurements of the model.
The 50mmx6mm angle is probably too wimpy so I think it will need a couple of full height triangular braces
I found a length of 42x22mm steel bar from I think a washing machine packing spacer so cut a length off with an angle grinder.
The 42mm needed reducing to 35mm so I chucked it in the 4 jaw, roughly centered it, reduced the speed to 350rpm and proceeded to remove the 7mm using a 1/2" round nose bit I had been given. I thought this would be a better proposition as this was a very interrupted cut and I was unsure what would happen to a 6mm cutter.
This was a very rough cut and I couldnt get it set low enough to the centre line so it left a large cone (too large to be called a pip).
I then ground a 6mm HSS cutter to a radiused end and stoned it sharp to use as a finishing cut.
I was astounded at the finish it produced so then decided to remove all the fire scale on all 6 sides to give a nice looking rectangular bar of steel. The 12mm square of plate its sitting on will be the base.
I learnt something very valuable in this exercise,
1, interrupted cuts produce very small but very very hot chips that raise tiny blisters. Ouch!
2, Using the rear of the jaws in the 4 jaw as a reference surface for the facing cuts is not a good idea, one of them may be slightly thicker than the others, the block of steel ended up 0.2mm difference from end to end and the end faces are not quite square. I'm hoping I can shim this square in assembly. Or maybe bite the bullet and file it square.
Next I drilled and filed a slot through the middle for the slide screw,As you can see I stopped before it was totally flat. I plead the weather, its 92'F and 80% humidity so I stopped.
I decided to use a length of 75x6mm cold rolled plate for the slide so had to remove 25mm from one edge. The metal is pitted but I'm hoping with a smooth up on some emery the pits will end up being oil holders.
)
The filed edge was reasonable till I blued it which showed up a nice hollow so it had to be scraped flat.
Eventually it became as flat as the other original milled side and of equal width across.
So now I scraped the cast slide flat as well.
I'm hoping this is sufficient flat surface as it runs the full length and will wear in evenly in use.
The pads were milled flat some time ago so I didnt have to touch those.
I hope I can get back to this asap but dont know when that will be.
I decided to make a small vertical slide to help in cutting the gear blank.
I had a small topslide casting already made for the Gingery lathe so thought I may as well use that as a starting point.
Everything else must come from the scrap bin (remember I'm stingy)
I cant produce engineering drawings and cant really read them either so I tend to work out my projects in an old 3d modeling/animation program to get it clear in my head and came up with this. It does mean I can check out clearances and fits before I cut anything as I can read the measurements of the model.
The 50mmx6mm angle is probably too wimpy so I think it will need a couple of full height triangular braces
I found a length of 42x22mm steel bar from I think a washing machine packing spacer so cut a length off with an angle grinder.
The 42mm needed reducing to 35mm so I chucked it in the 4 jaw, roughly centered it, reduced the speed to 350rpm and proceeded to remove the 7mm using a 1/2" round nose bit I had been given. I thought this would be a better proposition as this was a very interrupted cut and I was unsure what would happen to a 6mm cutter.
This was a very rough cut and I couldnt get it set low enough to the centre line so it left a large cone (too large to be called a pip).
I then ground a 6mm HSS cutter to a radiused end and stoned it sharp to use as a finishing cut.
I was astounded at the finish it produced so then decided to remove all the fire scale on all 6 sides to give a nice looking rectangular bar of steel. The 12mm square of plate its sitting on will be the base.
I learnt something very valuable in this exercise,
1, interrupted cuts produce very small but very very hot chips that raise tiny blisters. Ouch!
2, Using the rear of the jaws in the 4 jaw as a reference surface for the facing cuts is not a good idea, one of them may be slightly thicker than the others, the block of steel ended up 0.2mm difference from end to end and the end faces are not quite square. I'm hoping I can shim this square in assembly. Or maybe bite the bullet and file it square.
Next I drilled and filed a slot through the middle for the slide screw,As you can see I stopped before it was totally flat. I plead the weather, its 92'F and 80% humidity so I stopped.
I decided to use a length of 75x6mm cold rolled plate for the slide so had to remove 25mm from one edge. The metal is pitted but I'm hoping with a smooth up on some emery the pits will end up being oil holders.
)The filed edge was reasonable till I blued it which showed up a nice hollow so it had to be scraped flat.
Eventually it became as flat as the other original milled side and of equal width across.
So now I scraped the cast slide flat as well.
I'm hoping this is sufficient flat surface as it runs the full length and will wear in evenly in use.
The pads were milled flat some time ago so I didnt have to touch those.
I hope I can get back to this asap but dont know when that will be.
B
Bill Gruby
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Spindles by Harprit Sandhu. Workshop Practice Series #27. Page 92 has the spindle and mount you are looking for to cut gears in the lathe.
"Billy G")
"Billy G"
)
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- Aug 22, 2012
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Spindles by Harprit Sandhu. Workshop Practice Series #27. Page 92 has the spindle and mount you are looking for to cut gears in the lathe.
"Billy G"
Thanks Bill,
that is a better solution but needs a separate drive system that I dont want to get into just yet.
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- Aug 22, 2012
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In a bit of a halt at present.
Welder stopped working, replaced the liner with a shimano brake outer cable that has the plastic liner.
Very smooth now.
Snapped a 4mm tap in the middle of the way plate backing so now building a spark erosion machine to get it out.
(no plans as it wont be any where near suitable for a safety based culture)
Welder stopped working, replaced the liner with a shimano brake outer cable that has the plastic liner.
Very smooth now.
Snapped a 4mm tap in the middle of the way plate backing so now building a spark erosion machine to get it out.
(no plans as it wont be any where near suitable for a safety based culture)
- Joined
- Aug 22, 2012
- Messages
- 4,292
Hi Bill,
I have to eat humble pie here.
You were right the first time, the only ratio that counts is that between the first gear and the last gear in a gear train.
The different ratios between all the other gears cancel themselves out.
So, all those posts mentioning any gear can be used are correct and I humbly sit here apologizing to all and sundry.
Still, learnt something new and thats what it all about.
Now I must do the math and see how it affects a gear train with compounded gears such as the 127/120 combo.
Anyone care to chime in here?
Regards
Charles
I have to eat humble pie here.
You were right the first time, the only ratio that counts is that between the first gear and the last gear in a gear train.
The different ratios between all the other gears cancel themselves out.
So, all those posts mentioning any gear can be used are correct and I humbly sit here apologizing to all and sundry.
Still, learnt something new and thats what it all about.
Now I must do the math and see how it affects a gear train with compounded gears such as the 127/120 combo.
Anyone care to chime in here?
Regards
Charles
You are correct,I worded the other post wrong. My apology for the misrepresentation. Don't know where my head was when I posted that. I will delete that from the other post before it messes someone else up. It should have read "The idler needs to be the same sizs as the driver gear." Mine is the same as the gear on the spindle.
"Billy G"
- Joined
- Aug 22, 2012
- Messages
- 4,292
Re: tumbler reverse/ spark eroder
Its alive, its alive. AT last I have the spark eroder working in a lash up.
Its amazing, it burnt through 5mm of broken tap in approx 15 mins.
I'm using an enameled length of 3mm copper wire as the probe so it only contacted at the tip and not the hole walls.
Buzzing like a champion.
Then, oh! calamity, I think I shorted the power lead to the bench, the bridge rectifier cooked and so did the lead to the discharge cap.
I will see if the cap is usable tomorow.
These were very quick pics before it self destructed so bare with me, better ones to come (eventually)
if you look very closely you can just see the arc at the bottom of the probe, its actually down about 3 mm into the hole here and the kero is turning an opaque black, the surface ripples are from the unit vibrating as the probe slams up and down very fast.
Its alive, its alive. AT last I have the spark eroder working in a lash up.
Its amazing, it burnt through 5mm of broken tap in approx 15 mins.
I'm using an enameled length of 3mm copper wire as the probe so it only contacted at the tip and not the hole walls.
Buzzing like a champion.
Then, oh! calamity, I think I shorted the power lead to the bench, the bridge rectifier cooked and so did the lead to the discharge cap.
I will see if the cap is usable tomorow.
These were very quick pics before it self destructed so bare with me, better ones to come (eventually)
if you look very closely you can just see the arc at the bottom of the probe, its actually down about 3 mm into the hole here and the kero is turning an opaque black, the surface ripples are from the unit vibrating as the probe slams up and down very fast.
- Joined
- Aug 22, 2012
- Messages
- 4,292
Re-wired the machine and placed most bits inside the old welder.
It worked like a trojan, removed all the tap leaving the flutes inside that a poke with the scriber loosened sufficiently to fall out the hole.
The cut threads wernt touched so a quick clean up with a new tap and its back to work on the vertical slide.
Did I mention how impressive this operation was?
Heres an indication of how much tap was removed and a bolt fully in the repaired hole.
it would probably been quicker to make the part again but wheres the fun in that and I have another tool in the bargain
It worked like a trojan, removed all the tap leaving the flutes inside that a poke with the scriber loosened sufficiently to fall out the hole.
The cut threads wernt touched so a quick clean up with a new tap and its back to work on the vertical slide.
Did I mention how impressive this operation was?
Heres an indication of how much tap was removed and a bolt fully in the repaired hole.
it would probably been quicker to make the part again but wheres the fun in that and I have another tool in the bargain
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