Sunday, January 8, 2012

Changing Gears to Cut Threads

I had little time after reaching home and spent that 15 - 20 mins to change the gear according to the table provided on Proxxon manual and the gear box.  This is the first time changing such gears and I was careful to read the instruction over and over again before executing it.

The table is posted below (given in the manual and on the gear box):


The default setup was dis-assembled after pics were taken so that I can put them back in the same order.  The gear change went well except another cut on my middle right knuckle when the wrench slipped.  The cut wasn't as bad as the one I had when trying to remove the tool holder from the QCTP - the dovetails are really sharp! A small piece of skin and a little flesh came off.  This round, just a little broken skin with some bleeding.

This gear, with position labeled as 'L', gave me some problem in removing. The nut turns when I tried loosening it. I engaged the power feed (with the power turned off of course) and use the handwheel to hold the leadscrew while applying a little torque at a time.
The changes done. At the back of the 50-tooth gear (the one in the middle), there is a 30-tooth.  I didn't see any spacer other than the one on 'L' (the 60-tooth at bottom right), so the 20-tooth is used to act as one.  Hope that won't cause any problem.
View from the side.  The 30-tooth gear can be seen behind the 50-tooth (the 2nd gear from the bottom).

I did a "dry run" with the tool a distant away from the stock.  Everything seems to work alright.  The carriage moved at snail pace with 80 rpm selected.  According to the manual, I'm not to disengage the half nut during operation.  Just need to move the cross slide in, power one the lathe with the spindle turning anti-clockwise, turned the spindle off, back off the tool, reverse the spindle, reached the start of cut, turned spindle off, move in the tool for the next pass, and so on.  Seems easy enough.  I'll do another dry run till I can do it without thinking before proceeding with the cut.

I see that I have some time tomorrow night as my wife will be out meeting with her church friends. They're planning another visiting to some homes a month or two from now.  These meetings usually end rather late.  I should have the locking lever completed by tomorrow night.

One thing I've been thinking about on this project; If I'm to loctite the tommy bar to the bolt head, how do I remove it should I need to remove the clamping plate from the tailstock?

This is how the bolt looks currently.  The bolt is just a simple M8 capscrew.

The capscrew holds a steel clamping plate beneath the tailstock.

Anyone with idea please drop me a note.  Thank you in advance.

8 comments:

GeneK said...

Wong, lock tight is easily removed by heating to 300 -350 deg. F. That breaks the bond and then can be taken apart. Clean with acetone and you are all reset to start again.

GeneK

Wongster said...

GeneK,

I thought of that but worried it may do some damage to the tailstock. I guess it shouldn't, coming from you :-)

Threading with start tonight.

Regards,
Wong

GeneK said...

Wong, you have to learn to control the heat. In the case of a tommy bar stuck into the cam lock you are describing, you would have to turn it to a position where the end was as far away from paint and other delicate surfaces. Heat with torch or other device and let the heat conduct down the bar into the joint.
an alternate is to just cut the bar short enough to get things apart then heat the assembly away from the tail stock. Of course you then have to make a new bar.
Or maybe just thread the bar and use a weaker type of thread locker.

Wongster said...

I'll go with the weaker type of thread locker. Would medium do? I've a small bottle of that. Otherwise, I'll go get one weaker type.

Regards,
Wong

GeneK said...

I use the blue for most things, the red was used for smaller fasteners and the green is the 'permanent' sleeve retainer to really lock everything up tight.
I think the blue is what you are referring to as medium strength.

GeneK

Wongster said...

Should I be using blue or red? I've both?

Regards
Wong

GeneK said...

Wong, when I worked at ESI(electro Scientific Incorporated) we used blue on 10-32 and larger, the red we used on 4-40. I think the literature from lock tight had the dividing line at 1/4" and larger for the blue. I really don't believe it makes much difference on our size projects. I'm still using the stuff that was in my tool box when I left ESI in 2001.

GeneK

Wongster said...

That's almost CSI... Lame, I know. Lolz...

I'll just go with the medium strength stuff. Will torch it down if need be, hopefully not.

I've just received the books and DVDs from WR Smith. Flipped through a little, looks like I'll take sometime to understand what I need to do to make a skeleton clock. Deep stuff...

Regards,
Wong