tumbler reverse

savarin

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I'm looking into making a tumbler reverse for my 9x20.
I'm sort of following the 9x20 LATHE TOP MOUNT REEVERSE TUMBLER by
Jeremy Taylor.
I'm considering making the shaft for the reverse gear (45t in Jeremy's plans) to fit the 42t gear but making the position adjustable for a 45t when I can find one as I may need the 42 for threading at some time.

If I had some brass I would make a bush for the centre of the gear but I dont so would the cast iron gear running on a steel shaft (polished smooth) be ok?

I will also be using a chunk of 6mm steel instead of 3/8 aluminium plate because I have a lot of it and it looks as if there is sufficient clearance so the large steel plate bolted to the head of the lathe doesnt need cutting, fingers crossed.
Thanks
 

November X-ray

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You would probably be better off making a bushing out of steel and carefully press fit it into the gear and make sure to lube it often instead of just using the gear casting directly on polished steel. Of course if you could find some bronze, that would be even better or you could do what I did and use a roller bearing.

Good Luck.
 

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Oil-lite bushings come in just about every size, one of them would be ideal. Or, you can even get plain bronze bushes.

I use oil-lites a lot.

Steel on steel wouldnt be the first choice - cast iron on steel is good, and of course, brass/bronze, thats why you see CI gears riding on a steel shaft - or with a brass bush.
 
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For some unknown reason my computer is against me this morning. I can't import what I want.

SOOO ----- Google Tumbler Reverse on a 9X20 Lathe. You will find a PDF file there titled," Tricking Out the Asian 9X20 Lathe" In that file on page 11 I believe is the Tumbler Reverse I used on mine. It took only 2 or 3 houre to complete it. Super Simple.



"Billy G" :))
 
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That's the one and it link is OK. Thank you.

"Billy G" :))
 

savarin

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For some unknown reason my computer is against me this morning. I can't import what I want.

SOOO ----- Google Tumbler Reverse on a 9X20 Lathe. You will find a PDF file there titled," Tricking Out the Asian 9X20 Lathe" In that file on page 11 I believe is the Tumbler Reverse I used on mine. It took only 2 or 3 houre to complete it. Super Simple.

Remember this, the size of the idler gear is up to you, all it does is reverse the drive gear at the spindle. It will not change any speeds.

"Billy G" :))
I have seen that one but forgot all about it.
I thought that using the above the headstock handle would mean a longer lever thus allowing detant stops for forward, neutral and reverse further apart. I will measure this today to double check.
With regards to the size of the reverse gear not changing the speeds I just cant get my head around, I've seen it mentioned in a lot of places but cannot see why it wouldnt change the speeds.
If the spindle gear is 40T (what my lathe is) then the nylon gear (80T) is driven 1/2 a rev for every rev of the spindle gear.
If the reverse gear is 40T then it drives the nylon gear exactly the same per revolution, but, if the reverse gear is a different size then surely there is a discrepancy in the amount the nylon gear will turn per revolution of the spindle and this will affect how much all the other gears down the train turn.
Surely this would show as a difference between the revs of the spindle and the revs of the lead screw making a left hand threading operation slightly out of size.
 
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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" :))
 
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savarin

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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" :))
Phew! thanks for that Bill it was doing my head in as virtually all the posts I've seen state it make no difference but I couldnt see why it wouldnt make a difference.
Now I just need to find a 40T spur gear.
Time for some amber nectar I believe, have a good one.
 

swatson144

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Don't laugh but I made mine out of 3/8" plexiglass and it worked like a champ I recently removed it to make it out of steel. Steel will allow me to weld a better fixture for adjusting it but a pin and 3 holes worked well just not very techy.

tumble reverse.JPG
here it is freshly removed from the machine

tumblereverse2.JPG
I turned down hardware store bushings to fit the gears and made steel posts to fit the bushings simple wheel collars to hold it together and a washer for clearance. No harm to the original parts and it can be returned to stock simply enough.

tumble revers4.JPG
The needed cut away on the gear plate.

tumble reverse3.JPG
I modified the outline to make it easier to cut from metal. I have made a CAD drawing up and will likely let it loose after I finish mounting and testing. Work got in the way.

Steve

tumble reverse.JPG tumblereverse2.JPG tumble revers4.JPG tumble reverse3.JPG
 

savarin

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Still on the same track how do I work out if my gears are metric profile or imperial profile?
I will have to purchase a 40T spur gear for this job but have no idea if it is metric or imperial.
 

savarin

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Still on the same track how do I work out if my gears are metric profile or imperial profile?
I will have to purchase a 40T spur gear for this job but have no idea if it is metric or imperial.
Whoops! RTFM.
Metric module 1 20' pressure angle.
 

savarin

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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.

gear-cutter_zps3fde214b.jpg

gear-cutter2_zpsde8e801f.jpg

gear-cutter_zps3fde214b.jpg

gear-cutter2_zpsde8e801f.jpg
 

savarin

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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.
vert-slide.jpg
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).
facing1.jpg
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.
facing2.jpg
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.
facing3.jpg
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.
scraping1.jpg
Eventually it became as flat as the other original milled side and of equal width across.
scraping2.jpg
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.
scraping3.jpg
I hope I can get back to this asap but dont know when that will be.

facing1.jpg facing2.jpg facing3.jpg scraping1.jpg scraping2.jpg scraping3.jpg vert-slide.jpg
 
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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" :))
 

savarin

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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.
 

savarin

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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)
 

savarin

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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

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" :))
 

savarin

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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)

eroder1.jpg

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.
eroder2.jpg

eroder1.jpg eroder2.jpg
 

savarin

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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.
taps.jpg
it would probably been quicker to make the part again but wheres the fun in that and I have another tool in the bargain

taps.jpg
 

savarin

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Its been a long time since I got any shed time but managed a bit in the last week.

vert-slide-parts.jpg

Made the angle plate from 8mm plate and welded it together. Managed to control the welding distortion and kept it square.
I was rather pleased with the 8x1mm thread, it came out pretty good, not perfect but more than good enough.
The end of the feed screw was hand filed square (sort of) likewise the hole in the handle. It only has two ends because I couldnt turn a four handled one.
The aluminium casting is an old one from my gingery lathe (never finished)

vert-slide-scale.jpg

As I will be cutting a 40 tooth gear I needed a means of indexing it.
This site will print an index wheel for any divisions you want.
http://www.cgtk.co.uk/metalwork/divider
I used spray adhesive to stick the divider to a thin sheet of steel and sealed it with lacquer.

vert-slide2.jpg

The angles are bolted to the slide with 5mm c/sunk screws, 4 in each angle.
The shaft is 8x1mm, and is the best thread I've cut so far.
The gap between the top of the handle and the index wheel is actually larger than it looks in the photo.
Still have to make the pointer then its onto the lathe and have a go at cutting the gear.
No idea when that will be but I hope its soon. I was suffering from shed withdrawal symptoms.

vert-slide2.jpg vert-slide-parts.jpg vert-slide-scale.jpg
 
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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)

View attachment 47144

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.
View attachment 47145
How about doing a build on this one for us? I could use one of these at times.

"Billy G"
 

savarin

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Re: tumbler reverse/ spark eroder

How about doing a build on this one for us? I could use one of these at times.

"Billy G"
Me two please, seems like a good tool to have.
Brian.
 

savarin

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Re: tumbler reverse/ spark eroder

I've used it three times now and think its an excellent tool.
The one on the yahoo group is definitely superior and works faster but is more complex.
I followed this plan and circuit but used wood and what I had laying around.
http://www.homemodelenginemachinist.com/downloads/files/Easy_Spark_Eroder.pdf
I wound the coil on the plastic spool the wire came on, it was just the right inside dia.
The chuck came from an old clapped out battery drill.
Its really simple to follow and will give reasonable performance.
Instead of buying a large mains transformer I used an simple arc welder as the power plant as thats basically just a transformer.
 

savarin

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Whoo Hoo, it worked.
Heres the set up, note the bicycle saddle cam lock bolt used as a lathe saddle lock bolt.:thumbsup:

gear-cutting-1.jpg

Starting

gear-cutting-2.jpg

The final result.

gear-cutting-3.jpg

The aluminium one in the middle is the new gear.
Looks ok but this was just a test of concept.
In actual fact it rolls in one direction smoothly with no problems but reverse the direction and the teeth just catch a teeny teeny bit.
I think I didnt have the centre of the cutter exactly on a direct line to the central axis of the blank and so cut the gear teeth slightly off.
Considering that I only hand ground the cutter by eye and set the cutter on the blank the same way, never measured to find the depth of cut I'm still rather impressed with what I ended up with.
I set the blank position so the cutter just missed it, started the lathe and wound the vertical slide upwards. Slacken the nuts, move round one index mark, tighten and cut again.
When I got to the last tooth I re-set up to re-cut the first one again just to see if there was any difference.
It just made a slight hiss as it kissed the blank without cutting anything so it all lined up.
I think a little more care grinding the cutter and setting up square will produce excellent results.
It took approx 2 hours to cut all 40 teeth so its not fast but as I have no experience to relate to I dont know if this is good, bad or average.

gear-cutting-1.jpg gear-cutting-2.jpg gear-cutting-3.jpg
 

savarin

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At long last its finished and working.
I added a spring detente to make finding neutral easier and drilled the two new shafts so they can be oiled although I dont know why I did the reverse shaft as it cannot be reached :shrugs:

rt4.jpg

That chunky handle will be knurled once I get the tool.
Why so large? It was a left over from some casting.

rt3.jpg

I added a couple of cams at each end of the slot for exact placement of the gear shifter. Not my idea but I saw it somewhere and thought that was a goodie.
A huge problem I have is that virtually every gear (except the one I made:biggrin:) is oval and a real pain to align so they dont bind.
I made a new keyed centre for the 120/127 set that helped a little as even that was bored off centre and I can now get it running in forwards and reverse without them making the unholy noise they did but round gears would be so much nicer. I will have to make new extensions for the gear cutter to enable a 127 gear to fit it.

rt2.jpg

Plenty of clearance, I never had to cut the back plate but did replace one of the cap screws with a standard hex head bolt to get sufficient clearance for the reverse gear.

rt1.jpg

All in all I'm well pleased with the mod. Particularly with all the lessons learnt.
I've left the aluminium gear plain as I will cut another one and ensure I am spot on with the indexing and add a brass bush.
I could bore this one for a bush if it wears too much so I thought I would see how long it would take to wear out.
Next job, QCTP coming soon so do I alter the compound? Make a plinth for it?

rt1.jpg rt2.jpg rt3.jpg rt4.jpg
 
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Bout time you got that done, very nice. Now it's time for the autofeed cross slide. I'm almost done with mine.

"Billy G"
 

hman

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Next job, QCTP coming soon so do I alter the compound? Make a plinth for it?
I used the Little Machine Shop #3712 adapter post to mount an AXA (from CDCO) atop the compound on my G4000. http://littlemachineshop.com/products/product_view.php?ProductID=3712&category=

The adapter is just $10+shipping. Works well - I can lower 3/8" tools to about 1/16" below centerline. The adapter I got had a slight problem (10mm bore not deep enough) that I fixed with a 25/64" bit. I emailed them about this a month ago, and they replied they would check. They're a great outfit to deal with, and they probably have the issue fixed by now.
 

savarin

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Bout time you got that done, very nice. Now it's time for the autofeed cross slide. I'm almost done with mine.

"Billy G"
yer not wrong Bill, too many other projects preventing me from shop time.
The auto cross slide will be a long time coming.
I really must get on with the giant binos and the tilting trike now I can make more parts.
 
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