Where's Harry Potter when you need him ..... the Dark Arts ...... Grrrrr.. SPT
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BobWarfield
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Oh my, all this metric versus imperial versus 8 million gear combinations and which ones will fit on the banjo, yada, yada. So much pain.
And now, for the real black art secret: it's all so unnecessary and so last millenium (he said with tongue somewhat in cheek). After all, the computer can do for lathes what it has done for the phonograph.
CNC, of course, makes all of this easy. But CNC is such a religious issue. Many don't want to deal with CNC and all of it's learning curve and cost. But there is a waypoint between the mechanical and the full CNC that is pretty nice. It's called an "Electronic Lead Screw". Here is a YouTube video:
[ame]http://www.youtube.com/watch?v=RRaVIBhLgF0[/ame]
So what you do is mechanically use a stepper motor to drive your leadscrew. It's not hard to lash one on there. You attach a little sensor to the spindle, which enables the little computer (it's all in a box, you don't need a separate PC, just mount the little box right on your lathe next to you VFD) to create an infinitely variable simulated gear train. Now you can dial in any thread or feedrate you might want.
If you are more ambitious, the ELS can control both axes and do tapers of any kind, but now you really are starting to get more down the road to CNC. I just love the idea of an infinitely variable electronic gear box that is cheap and cheerful to put in place on almost any lathe.
Here is the Yahoo Group for the thing:
http://tech.groups.yahoo.com/group/E-LeadScrew/
There are professional "manual" lathes that have this feature. A Hardinge clone is pictured on the site. John Danmeyer manufactures the little kit and frequents the HSM boards. He may even be lurking here.
Worth a look see. Short of CNC I can't imagine a more versatile answer to this vexing problem.
Cheers,
BW
And now, for the real black art secret: it's all so unnecessary and so last millenium (he said with tongue somewhat in cheek). After all, the computer can do for lathes what it has done for the phonograph.
CNC, of course, makes all of this easy. But CNC is such a religious issue. Many don't want to deal with CNC and all of it's learning curve and cost. But there is a waypoint between the mechanical and the full CNC that is pretty nice. It's called an "Electronic Lead Screw". Here is a YouTube video:
[ame]http://www.youtube.com/watch?v=RRaVIBhLgF0[/ame]
So what you do is mechanically use a stepper motor to drive your leadscrew. It's not hard to lash one on there. You attach a little sensor to the spindle, which enables the little computer (it's all in a box, you don't need a separate PC, just mount the little box right on your lathe next to you VFD) to create an infinitely variable simulated gear train. Now you can dial in any thread or feedrate you might want.
If you are more ambitious, the ELS can control both axes and do tapers of any kind, but now you really are starting to get more down the road to CNC. I just love the idea of an infinitely variable electronic gear box that is cheap and cheerful to put in place on almost any lathe.
Here is the Yahoo Group for the thing:
http://tech.groups.yahoo.com/group/E-LeadScrew/
There are professional "manual" lathes that have this feature. A Hardinge clone is pictured on the site. John Danmeyer manufactures the little kit and frequents the HSM boards. He may even be lurking here.
Worth a look see. Short of CNC I can't imagine a more versatile answer to this vexing problem.
Cheers,
BW
B
Bogstandard
Guest
Dave,
With this problem, IMO you are doing the right thing. Hanging on to the bitter end, until you have proved either success or failure.
By doing it this way, unlike a lot of others, who would have given up and reverted to taps and dies, you are deep into a major learning curve. Get it cracked, and you will be whistling and grinning for all time. You should be able to accurately cut threads on your lathe.
If it doesn't work out, and you can't get good results because of machine limitations, at least you will know it is not your fault, but you will know how a screwcutting gear train works, and the next time, on another machine, you might have more favourable results.
Keep at it mate.
John
With this problem, IMO you are doing the right thing. Hanging on to the bitter end, until you have proved either success or failure.
By doing it this way, unlike a lot of others, who would have given up and reverted to taps and dies, you are deep into a major learning curve. Get it cracked, and you will be whistling and grinning for all time. You should be able to accurately cut threads on your lathe.
If it doesn't work out, and you can't get good results because of machine limitations, at least you will know it is not your fault, but you will know how a screwcutting gear train works, and the next time, on another machine, you might have more favourable results.
Keep at it mate.
John
DickDastardly40
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CrewCab said:DD40 ......... in answer to your earlier questions
Carbide tipped 60o spt tool, between 5 and 10 thou, 100rpm, cutting steel rod, new lathe tool and the end of the tip broke off, spray on cutting fluid (aerosol) .............. direct approach ........... cross feed parallel to bed.
I can't see why you should get tool should breakage using the above method. At which point in the cutting process did the tool break. 100 RPM is possibly the slowest speed possible on your lathe yes? Is the steel rod mentioned silver steel drill rod? (as John says, this threads awfully).
I always try to have a recess at the shoulder end of the thread to run the tool into. Others back the tool out swiftly at the end.
Possibly if you are not running the tool into a recess at the end of the thread and you don't either manage knock out the leadscrew feed or stop the lathe (if not disengaging the half nuts) at the same time every time, the pressure on the tool as it reaches the end of thread and tries to cut full depth could cause it to break.
Winding the spindle by hand for the last turn to get a dead nuts on stop has been covered before; Marv and Tel have both posted pictures of their respective 'mandrel handles'.
Hope the above helps. Lots of cracking information in this thread already.
Al
To remove the boss, will a puller along these lines work?
http://www.justoffbase.co.uk/Bearin...970e9dd33f599c3e.e3eTaxaQbxmTe34Pa38Ta38Mahb0
http://www.justoffbase.co.uk/Bearin...970e9dd33f599c3e.e3eTaxaQbxmTe34Pa38Ta38Mahb0
I had one similar some years ago on a new lathe where I had to pull the gear off with a puller and the sleeve wouldn't move.
After trying numerous tricks I drilled down it from the face and split it off then made a new sleeve with clearance.
They don't need to be dead nuts tight it's only a spacer and often the most destructive way does the least damage, read bent shafts, and is quicker in the long run.
If you get a blank, doesn't even have to be steel, any free machining material will do, mark out where the key goes, drill a hole then bore the centre out, clean up with a file.
Don't worry about a fit , it's only a spacer. Depending on what spare gears you have with the machine you may be able to use one of these as a spacer to save making one.
After trying numerous tricks I drilled down it from the face and split it off then made a new sleeve with clearance.
They don't need to be dead nuts tight it's only a spacer and often the most destructive way does the least damage, read bent shafts, and is quicker in the long run.
If you get a blank, doesn't even have to be steel, any free machining material will do, mark out where the key goes, drill a hole then bore the centre out, clean up with a file.
Don't worry about a fit , it's only a spacer. Depending on what spare gears you have with the machine you may be able to use one of these as a spacer to save making one.
Thanks guys, seems like it's a common problem then ???
I'll have a go with a puller etc, failing that methinks sacrificing the sleeve may be the best way forward, could well be the weekend before I get chance to have a look but I'll keep you all informed 8)
CC
I'll have a go with a puller etc, failing that methinks sacrificing the sleeve may be the best way forward, could well be the weekend before I get chance to have a look but I'll keep you all informed 8)
CC
CrewCab said:
;D ............. OK ............. I lied :big:
:big:Just snuck half an hour off to have another go at the lathe ............. it seems the "thorough" talking to I gave the Darn boss, ........... perhaps coupled with the penetrating oil ............. has had an effect, the bloomin thing virtually fell off of it's own accord as soon as I showed it a puller :
So, quick tidy up of the woodruff key with a file and both boss and gears slide on & off just fine ............
and ...... Problem Solved, it is a Metric Lead screw and now it's cut a first class 1.75 pitch thread in Delrin :bow: Thanks for all the help guys 8)
I'll try some aluminium at some stage before working back up to steel
CC
mklotz
Well-Known Member
CC,
Congratulations on your success. If nothing else, you probably have learned a bit about threading; though I expect you would have preferred a less taxing education.
Somewhere along the line, I've lost track. What exactly was your original problem with cutting the thread? Was it that you were misreading the gearing charts on your lathe or something else?
Congratulations on your success. If nothing else, you probably have learned a bit about threading; though I expect you would have preferred a less taxing education.
Somewhere along the line, I've lost track. What exactly was your original problem with cutting the thread? Was it that you were misreading the gearing charts on your lathe or something else?
To be fair Marv, I've enjoyed it as I've learnt a lot
As regards loosing the plot, don't worry your not alone ??? .......... The main problem was self inflicted, I thought my lathe was imperial, but as we now know it has a metric leadscrew and, having now resolved the seized bush and fitted the correct combination of gears it works just fine.
I've used a lathe quite a lot but that was many years ago, but I've never before attempted single point threading, without the help of the guys on here, particularly JohnS, I suspect I'd have been weeks getting to the bottom of the problem, but with all the help on this forum it's taken a couple days :bow:
CC
As regards loosing the plot, don't worry your not alone ??? .......... The main problem was self inflicted, I thought my lathe was imperial, but as we now know it has a metric leadscrew and, having now resolved the seized bush and fitted the correct combination of gears it works just fine.
I've used a lathe quite a lot but that was many years ago, but I've never before attempted single point threading, without the help of the guys on here, particularly JohnS, I suspect I'd have been weeks getting to the bottom of the problem, but with all the help on this forum it's taken a couple days :bow:
CC
mklotz
Well-Known Member
I guess my question is: Had you fit the gears indicated on the charts for the pitch you wanted to cut (1.75 mm IIRC), would it have worked correctly? What I'm after here is whether we need to warn other users of this lathe about a possible chart problem?
B
Bogstandard
Guest
Well done Dave,
Problem solved, lesson learned, the hard way maybe, but you can be damned sure you won't forget what you have learned.
John
Problem solved, lesson learned, the hard way maybe, but you can be damned sure you won't forget what you have learned.
John
