Threading at 400 RPM

Hello Chris, you are correct the number of teeth on a idler do not matter. The ratio only changes when two gears are ganged together with the with the drive coming on one gear and the output is taken from the other. The number teeth is arbitrary the idler gears could have been 32 teeth or perhaps 28 teeth. The overall load on this gear train is not very high while I do not have exact measurements shifting from forward to neutral to reverse while running 400-600 rpm is done with only a light click from dog pin engaging the next gear. Likewise when threading the carriage stops within about 0.002-0.005" consistently.

In the clutch the dog gears are 40 teeth and the output gear is 40 teeth and they are ganged together under load but since they are the same size there is no change in the overall gear ratio. The easiest way to think about this is to count teeth. If you move the driving gear through an arc that is equal to say 10 teeth then the idler gear no matter the size will likewise move through an arc of 10 teeth.

Jim
 
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I was really excited until I realized my subscription was with Machinist's Workshop. Still, I've got enough info to get me in real trouble with my Southbend 10L. Thank you for taking the time to document the mod and provide the info here.
 
Rick Leslie said:
I was really excited until I realized my subscription was with Machinist's Workshop. Still, I've got enough info to get me in real trouble with my Southbend 10L. Thank you for taking the time to document the mod and provide the info here.
Click to expand...

Hello Rick, if you run into trouble or are missing some key info let me know.

Jim
 
Thanks Jim for a great project and the time it must be taking to document and further explain!

I have read the post but still am unable to understand what retracts the crossfeed at the end of the travel?
Could very well have read it but it didn't click in my mind, what's left of it :D

Ken
 
The operator has to retract the crossfeed at the end of travel. It is not automated.
 
Are you 100% positive on that?
Sure looks automated on retract, I see where he manually adds .005 feed.


Edit:
OK, found another video that shows the retractor he made and uses, very slick and with that the confusion is now gone.
 
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The Grizzly G0602 is a very basic lathe with very few refinements. However, it provides a good foundation for the price and is of a size that will work well for most hobbyists. This sets up a situation where adding enhancements provides not only better functionality but a number of interesting projects. In my opinion of the changes that I have made the following is how I rate them.

1. Variable speed drive. This is the first change that should be made, the original belt system quickly become a pain.
2. Digital readout on the "X", "Y", and tail stock. The dials on the G0602 are graduated in inches but the lead screws are an approximation since they are threaded in mm's.
3. Cross slide retractor - This is a terrific improvement that comes in handy when threading or doing finish cuts I prefer the cross slide retractor to the top slide retractor but either is great improvement.
4. Threading clutch - this not only is a great addition for threading it also replaces another feature I added which is the reverse idler gear. The threading clutch project is the most challenging and also the most rewarding. If you avoid projects that require threading, using the clutch will send you in the opposite direction.
5. Index wheel - at some point you will want to make a dial or knob that is calibrated and the index wheel provides the ability to calibrate dials in increments of one degree for 360 degree dials or sub multiples, or, 1.8 degree increments for dials that need base ten marking.

There are numerous other smaller improvements such as a cam lock for the tail stock, improved retainer knobs for the gear train, carriage lock, etc. The threading clutch is one of a number of improvements that this lathe cries out for. If anyone needs help or information on these items let me know.

Jim
 
Fantastic. I ordered the jan/feb and march/april issues of HSM.

my HF 12x36 lathe is a bit different being there is a reverse gear assembly in the head. However I see Muzzy on the model-engineer site has worked out a simplified(?) version on his Colchester Bantam. It appears to use a similar gear train setup as the import 12x36s. http://www.model-engineer.co.uk/forums/postings.asp?th=49358&p=12

Hopefully I'll be able to work something out.
 
Jar944, good luck with your project. If you have any questions as you go along let me know. There are two dimensional errors in magazine text the first error was corrected with an errata in the second issue. The second error concerns the width of the key way in the output shaft. The text shows it as 0.125" but it should match the key width of your gears which is 5mm or 0.196". I made this by using a 0.1875 slot drill and making two passes. I used brass for the key material, the shaft load is modest.

Jim
 
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