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John Stevenson
07-12-2011, 02:15 PM
OK before someone gets it in first.

CLUMSY BASTARD :D

Rushing a job to get finished tonight [ always the case and in this case it isn't finished :mad: ] and this lump of scrapbinium {tm} comes hurtling out the chuck, removing the tool which I haven't found yet, shearing the bolts holding the toolpost on and throwing it on the deck.

So far all cosmetic but the force of throwing this lot all over pushed the saddle back at warp speed and removed two teeth off the handwheel pinion. Rack is hardened and is fine and the pinion shaft is also hardened.

I dare say I can get a new shaft but liable to be a couple of weeks waiting, could get a pinion and stub it onto the shaft, again two days.

What to do ?

Answers later, off down the pub for a meal and cry.

Bill in Ky
07-12-2011, 02:37 PM
I'm thankful that you were not hurt.
Machines can be fixed.

gwilson
07-12-2011, 02:38 PM
Blimey,'is lathe is knackered.

Can't you make the parts? I've had to do that before,but have no idea about your lathe. Do you have another lathe? I have 2,which is handy if I need to make parts for one that breaks down. You probably could turn simple turnings like the shaft and pinion gear with your milling machine,and cut the teeth in a small gear.

Toolguy
07-12-2011, 02:43 PM
Too bad you haven't got a POS Bridgy, you could make a new pinion gear in an hour or so.:( Oh wait - you DO have one! What a fabulous stroke of luck that is!:p Now you can get that lathe going again in no time!

Alistair Hosie
07-12-2011, 02:53 PM
Buy new John it is always better to have anew part than a fixed part.No slur intended on your excellent workmanship.
MY new saw should have come with a micro adjuster about the size of your finger with a small pinion on it and two free bronze bushes which get tapped into make a tight fit .It's small with a plastic handle it cost me seventy quid inc post and I am glad I bought it I can set the woodsaw up to within a 32'nd of an inch and it cuts just that.The fence has a steel pipe which carries a rack underneath it took me all day to figure out what was wrong/or rather how it worked as the brochure is not good at explaining that part,. So you have abig advantage over me a proper brain. Alistair

Zahnrad Kopf
07-12-2011, 03:00 PM
I dare say I can get a new shaft but liable to be a couple of weeks waiting, could get a pinion and stub it onto the shaft, again two days. What to do ?

Fret not, old sod... I'm sure SOMEONE here is just WAITING to give you the shaft~! :eek: :D

WJR

Boostinjdm
07-12-2011, 03:07 PM
Are you worried about any damage to the chuck jaws or spindle? I had a little incident with a parting tool a while back and now my 10" 3 jaw is all out of whack. I don't even know where to start looking for the error. My 6" is still fine so I'm assuming the spindle is alright.

lazlo
07-12-2011, 03:15 PM
Is that the TOS? Weren't you planning to get rid of it?

John Stevenson
07-12-2011, 04:22 PM
Yup it is the TOS but the small one, about 14 x 40 size.
Big one is still here and so is the CVA so not short of lathes just that this one does all the work.

Got it all stripped down before I knocked off for the night so decided to make a new shaft with the pinion as part of the shaft as it was and get it hardened. Not got a MOD 1.5 hob but I'm sure I can borrow one from the gear cutting company in the morning.

http://www.stevenson-engineers.co.uk/files/TOS_pinion_shaft.jpg

philbur
07-12-2011, 04:33 PM
Rumour has it that Myfords are real cheap this week.:D

Phil:)

Alistair Hosie
07-12-2011, 05:43 PM
I'll bet you there not cheap ,they'll be a big turn out although I think they should have prostponed it for a month or so to give people time to get some money together now it will go to the wealthier clients. Alistair

lakeside53
07-12-2011, 09:40 PM
Knowing it can happen to the best, I now I feel better after programming my CNC bridgeport to friction weld my pristine drill chuck to my immaculate Kurt vice.:(

wierdscience
07-12-2011, 10:04 PM
Sheesh,just don't use those two teeth:D

macona
07-12-2011, 10:11 PM
Knowing it can happen to the best, I now I feel better after programming my CNC bridgeport to friction weld my pristine drill chuck to my immaculate Kurt vice.:(


Oh yeah, Yesterday I inadvertently tested out how powerful the new Z servo motor on the knee is. Left the jack I was using to block the knee while I was working under it and homed. Snapped one of the two 3/8" tie bolts, pulled the threads off the other and bent the 3/8" steel end cap for the pneumatic cylinder. About a half hour with a hydraulic press and welded up the bolts.

I turned the max torque down to 50% after that...

Black Forest
07-13-2011, 12:22 AM
Do it the Redneck way! Build up the two broken teeth by welding and then get out the hand files!

DATo
07-13-2011, 12:38 AM
Probably best to buy new but just for the heck of it, if it were mine I'd try tig welding the material back on in layers and recutting the two teeth. Easy to pick up with an involute cutter given the fact that the other teeth are still in good condition. Might consider a copper collar somewhere in the area of the oil grooves to take up heat and prevent warping during welding. Tedious, but I would do one tooth at a time to minimize heat distortion of the shaft, but, frankly, I don't think that will be an issue.

Forrest Addy
07-13-2011, 01:08 AM
I see the pinion is integral wih the shaft. Can you take data from the existing gear and find a stock gear that can replace it?

Then turn down the existing shaft and key the replacement to it? In the mean time you can run the carriage with the lead screw and half nut using fine thread settings in lieu of feeds. Maybe re-position change gears in the index train to halve the available pitches. Of course you have to reassemble and reinstall the apron and the rest. I don't suggest you do it unless you really need that particular lathe. Sorry. This is pretty basic. I only mention the obvious because when I get in a dither the obvious is the first thing I overlook.

You can set a lead train selector handle in neutral and run the lead screw with strap wrenches for hand positioning. PITA but it will work for when you absolutely, positively etc.

fixerdave
07-13-2011, 02:03 AM
Oh yeah, Yesterday I inadvertently ...I turned the max torque down to 50% after that...
Please post more of this... us poor beginners can only handle so many pictures of immaculate 1/3 scale T5 transmissions and 302s without crying. We need more encouragement to get back into the game.

I'd list all the mistakes I made but I expect there's a text limit on this forum ;) Mistakes are about the only thing I reliably turn out in my little shop. Well, I make the occasional plan, sometimes an excuse or two.

A.K. Boomer
07-13-2011, 06:41 AM
I hate that uncontrolled inertia thing - hate it when that happens,

glad you weren't hurt SJ - you better slowdown and smell the cutting fluid once in awhile, you have a ton of repair options in front of you and you already know what they are - so the question really is - to repair or replace - yes - that is the question.

Black_Moons
07-13-2011, 07:04 AM
Id replace it, while repairing it would be wonderfuly easy for a slow speed, low torque (Well, at least that was the design for it!) gear, You also want there to be no error/lumps in the gear, or they WILL show up in your finish, if your lathe is like mine, it uses the feed rack/pinion for power feeds, So any lumps/errors in the pinion gear will show up in all your finishing feeds.

John Stevenson
07-13-2011, 08:43 AM
Well Nearly.

Decided due to the fact some twat of a customer brought shed loads of work in this morning that I'd repair it seeing as I did a drawing last night.

So ordered an off the shelf gear, 2 days delivery and set to. This way i can have a spare shaft waiting in the cupboard, sods law says that whilst you have a spare the original won't break.

Ground all the broken teeth away and bit into the gear so the transition point of the weld is below the teeth.

http://www.stevenson-engineers.co.uk/files/TOS_pinion_shaft2.jpg

The washers are offcuts of oilite bushes to keep splatter off the shaft.

http://www.stevenson-engineers.co.uk/files/TOS_pinion_shaft3.jpg


New teeth hiding under all that weld, skimmed up on the other lathe and into the dividing head on the POS Bridgeport, division master set to 17 divisions and a fly cutter ground up as I didn't have any gear cutters close.

Didn't realise not got a pic until into the build up. washed all the gearbox out and fitted shaft, had a clean round whilst the apron / gearbox, saddle and cross slide was off.

http://www.stevenson-engineers.co.uk/files/TOS_pinion_shaft4.jpg

Everything in position but not in mesh as the saddle holds everything in relation.

Saddle on, runs nice, just needs the cross slide on and fill the gearbox with oil and a bit of a clear up. reckon another hour.
Oh and then try to find the lathe tool that went flying !!

A.K. Boomer
07-13-2011, 09:05 AM
Oh and then try to find the lathe tool that went flying !!


yeah good luck with that one - happened to catcha pic or two in the past of how tidy a shop floor you keep:rolleyes:

Good duty though SJ - back and running already, nice.

TexasTurnado
07-13-2011, 10:52 AM
yeah good luck with that one - happened to catcha pic or two in the past of how tidy a shop floor you keep:rolleyes:

Good duty though SJ - back and running already, nice.

I always maintained that a clean shop was where little work was done and a dirty shop indicated so much work was being done the owner didn't have time to clean up often....:D :D

Weston Bye
07-13-2011, 11:17 AM
I always maintained that a clean shop was where little work was done and a dirty shop indicated so much work was being done the owner didn't have time to clean up often....:D :D

Some cleanup is necessary. Reminds me of using the toilet; the job ain't done until you're finished with the paperwork.:eek:

gwilson
07-13-2011, 01:00 PM
So, the answer "what to do" was to get going and fix it.

Good job,John. I wonder how strong the built up teeth from weld will be,though.

I'd have turned the shaft down and made a new gear. But,it should do you until parts arrive,at least.

TexasTurnado
07-13-2011, 01:01 PM
Some cleanup is necessary. Reminds me of using the toilet; the job ain't done until you're finished with the paperwork.:eek:

Absolutely - when it takes too long to remember where you put that tool you used last week, it's time to stop and put things back where they belong and clean up.... :D

Toolguy
07-13-2011, 01:11 PM
I think the weld is a good fix. Should last a long time, barring any similar accidents.

Peter.
07-13-2011, 01:19 PM
Nice repair!

That would have taken me three days :D

TexasTurnado
07-13-2011, 01:28 PM
So, the answer "what to do" was to get going and fix it.

Good job,John. I wonder how strong the built up teeth from weld will be,though.

I'd have turned the shaft down and made a new gear. But,it should do you until parts arrive,at least.

If the weld has good penetration and the rod a good match for the base material, it should be as strong as the weld metal - and if the gear was only Rc = 30 to begin with it should be nearly equal to the original....

Like Sir John said, if he has a replacement on hand, he will never need it.:D

I did something similar to the pinion on my Colchester, but it was building up the worn teeth with TIG welding and then remachining:

http://i288.photobucket.com/albums/ll168/TexasTurnado/P7140009.jpg

http://i288.photobucket.com/albums/ll168/TexasTurnado/P1010033.jpg

When I get time, I am going to make a new one with my hobber from 4140PH, but I first need to figure out how to cut the spine for the other gears.

Black_Moons
07-13-2011, 03:27 PM
Any detectable defects in your surface finish after this repair job?

I doubt much strength is needed really. Its one of those things that should only wear slowly, or snap in a crash. Its the accuracy I would worry about.

John Stevenson
07-13-2011, 03:42 PM
BM,
Not turned anything as yet, still looking for that damn lathe tool :rolleyes:

Might pop back in now I've had my tea and crank a lump of something up.

Watch this space.

John Stevenson
07-13-2011, 04:20 PM
Sorry for the delay, had to pick small son up from the bus stop.

Well chucked up a lump of hot rolled at 1 1/2" diameter, one pass at 4mm, 1400 rpm feed about medium.

http://www.stevenson-engineers.co.uk/files/TOS_pinion_shaft5.jpg


This lathe has two knobs on it for feeds, A and B, both go 1 to 5 so 1 - 1 is the finest and 5 - 5 is bloody quick. no idea what they are in feed per rev, never had the book out.
This was done on 3 - 3 which is what I use for everything.

Found the lathe tool, identical to the one in use and believe it or not it hadn't damaged the tip :eek:

Wish for some things it had smashed the tip and pocket instead of the gear.

TexasTurnado
07-13-2011, 04:32 PM
Any detectable defects in your surface finish after this repair job?

I doubt much strength is needed really. Its one of those things that should only wear slowly, or snap in a crash. Its the accuracy I would worry about.

Mine turned out accurate enough to run smoothly end-to-end - which is all it needs. Threads are cut by the leadscrew and the Colchester only uses the rack for fine feeds while turning (on this 15 x 50) - presumably that's why it was worn as much as it was....

Black_Moons
07-13-2011, 04:34 PM
Mine turned out accurate enough to run smoothly end-to-end - which is all it needs. Threads are cut by the leadscrew and the Colchester only uses the rack for fine feeds while turning (on this 15 x 50) - presumably that's why it was worn as much as it was....

Yea I know (any decent) lathe has the leadscrew for threads and the rack for power feed, but iv heard of lathes puting little defects in the finish, traced down to a bad gear in the power feed drive train, Hence why I asked.

Very good repair job if theres none to be seen! Better then some lathes come outta the factory apparently :)

franco
07-14-2011, 09:45 PM
Yea I know (any decent) lathe has the leadscrew for threads and the rack for power feed, but iv heard of lathes puting little defects in the finish, traced down to a bad gear in the power feed drive train, Hence why I asked.

Very good repair job if theres none to be seen! Better then some lathes come outta the factory apparently :)

My neighbor set up a new Chinese 12X36 lathe straight out of the crate recently. The carriage handwheel was initially very hard to turn, but soon freed up and the carriage stopped moving. The vendors, being 1200 miles away, didn't want to know about it, but said they might have someone in the distict sometime in the next six months(!) who could look at it then. They did volunteer to supply new parts though if the owner would do the work.

The rack gear shaft is 128 mm long including the 30 mm long rack gear. The shaft is 16 mm diameter and the gear, which is machined in one piece with the shaft, is about 25 mm diameter. The shaft is mounted in bushes each end, with an unsupported length of about 60 mm between the bushes, with another gear mounted about the middle of it. The roll pin locating this gear had sheared. The rack gear shaft was bent 0.035 in.TIR just outside the rack gear end bush. I'm still trying to work out how the manufacturer managed to do this! Considerable force would have been required to bend the shaft.

There is no visible sign of external damage to the lathe or damage to any other apron components except the bore of the gear in the middle of the pinion shaft, which was badly scored by the broken roll pin. No spares for this gear are available in Australia, but a new rack gear shaft was supplied without the roll pin hole for the intermediate gear. The intermediate gear bore was cleaned up as well as possible, and the lathe is now usable.

By the way there was quite a lot of casting sand in the bottom of the apron, so cleaning up after this mishap probably averted trouble later after the sand had time to damage the gears.

franco

The Artful Bodger
07-14-2011, 11:26 PM
[/B]

My neighbor set up a new Chinese 12X36 lathe straight out of the crate recently. The carriage handwheel was initially very hard to turn, but soon freed up and the carriage stopped moving. The vendors, being 1200 miles away, didn't want to know about it, but said they might have someone in the distict sometime in the next six months(!) who could look at it then. They did volunteer to supply new parts though if the owner would do the work.

The rack gear shaft is 128 mm long including the 30 mm long rack gear. The shaft is 16 mm diameter and the gear, which is machined in one piece with the shaft, is about 25 mm diameter. The shaft is mounted in bushes each end, with an unsupported length of about 60 mm between the bushes, with another gear mounted about the middle of it. The roll pin locating this gear had sheared. The rack gear shaft was bent 0.035 in.TIR just outside the rack gear end bush. I'm still trying to work out how the manufacturer managed to do this! Considerable force would have been required to bend the shaft.

There is no visible sign of external damage to the lathe or damage to any other apron components except the bore of the gear in the middle of the pinion shaft, which was badly scored by the broken roll pin. No spares for this gear are available in Australia, but a new rack gear shaft was supplied without the roll pin hole for the intermediate gear. The intermediate gear bore was cleaned up as well as possible, and the lathe is now usable.

By the way there was quite a lot of casting sand in the bottom of the apron, so cleaning up after this mishap probably averted trouble later after the sand had time to damage the gears.

franco


Franco, I expect you could bend that shaft by not having the rack pinion properly engaged with the rack when you tighten the cap screws that fix the apron gearbox to the top of the saddle.