Yet another PM-1236

[tino_ale]

Ok here is my table (metric machine) :

and

Right now the machine is in configuration where top = 24, middle = 120, bottom = 48 and both top and bottom mesh on the 120 side.

I just can't see how I'm supposed to switch to the second metric configuration without flipping over the middle gear.
To me the drawing is clear that both mesh on the 127T side of the middle gear, with the 48 up and the 24 down.
Look at the configuration to cut imperial threads, in that particular case yes it is very clear that both sides of the middle gear are used at the same time.

Do I make sense ?

 

[darkzero]

Now I see your confusion. Your chart is much different, not consistent with my chart for metric vs. imperial. I'm very familiar with how my lathe works so I doubt yours would operate much different. Looking at your chart makes me think the gear configuration diagrams are mislabeled. How yours is labeled for the middle gear for metric does not make any sense according to the top & bottom gears. You should only need to use the 120T for metric & the 120T to 127T for imperial just as it is for mine vise versa.

I think your best bet is to contact Matt. I can't think of anyone here that has the PM1236 in metric as ordered (only the guys who received metric by mistake) that could give you advise.

I still think what I said is how it should be used despite what your chart diagram for the gears say. For instance, lets look at your chart for cutting a .4mm pitch thread B4, MI, 24T-120T-48T. Focus only on the B4 column, now when you switch to MII it doubles, hence the .8mm pitch. Now when you switch the top and bottom gears to 48T (on top), 120T, 24T (on bottom) it doubles again giving you 1.6 & 3.2. But for 1.6 & 3.2 it says to use the 127T instead of 120T. I think that is wrong. If you did use tbe 127T like it says, that would give you a totally different thread pitch rather than doubling the previous thread. Look at my chart below & for imperial which my lathe is configured for vs yours metric, it does not specify what the middle gear tooth is meaning the inner gear of the double set would be used, make sense?

So do this, try cutting a 1.6mm pitch thread. B4, MI, 48T on top, but use 120T instead of what the chart says (using 127T), then 24T on bottom meshing to the 120T. I bet it will cut a 1.6mm thread. Then switch to MII & it should cut a 3.2 thread. Please do that & let us know the results.


(Sorry for the bad pics, it's what I had on hand)

 

[tino_ale]

Thanks for taking the time, thank you !

Looking at your chart I also notice that your feed tables are different for the metric and imperial section : you are using both sides of the 120/127T gear to achieve metric feed. Which makes sense. Your imperial values are a bit different than mine.
On my chart, the settings are the same for both metric and imperial feed values, and the imperial values seem to be simple rounded value in inches of the metric values.
It's just feed values, not worried about that.

I will wait for my gear extractor that I have ordered to arrive (my gears are stuck...) and will definetely try what you advise.
I must admit I did not imagine the chart could be wrong. But that would be the best imaginable outcome.

 

[tino_ale]

OK I haven't tried it yet but gave more thoughts to it.

What Darkzero said makes perfect sense.
B4 column, speed I, the pitch is x4 from the first to second gear configuration.
KEEPING THE SAME MIDDLE GEAR, going from 24T to 48T gear at the top would double the pitch.
On top of that, going from 48T to 24T on the bottom gear would double that again.
in B4 column, we go from 0.4 to 1.6 pitch, that is x4, makes PERFECT SENSE.

BRAVO for the heads up. I did not think outside the box, I feel dumb !!
I still can't believe they actually printed a wrong table!

Problem solved. Will check for good measure but I know it's right.

 

[darkzero]

Dumb, not at all. Things are often overlooked or not thought of when you are focusing at the "issue" at hand. We've all been there. That's what these forums are for, to get other opinions. Again, I'm sure the gear chart diagrams for your lathe is not right, but once you confirm if it's right or wrong you can move forward.

 

[srbh]

Room at the back. I added 50cm but later found on the internet that more was recommended. The more the better, especially if you need access to shelves etc on the wall. I have cut a new hole in the tailstock end cabinet to access the coolant pump from the front.

 

[tino_ale]

Hi guys,
Investigating those motor issues (see other thread), I found an oil leak at the back of the pulley arbor.
Disassembled the whole gears section.
Cleaned every single part.
Blasted the gears and parts (I didn't like the way they looked)
Fixed the leak and reassembled.

I don't think my gear assy will ever look as neat again !

I gave a shot at machining brass. Alloy is free cutting brass (alloy 360).
What a blast ! super easy to machine, nice little chips, finishes really well, shiny and sharp look.
I loved it !
Made a replacement "knob". Much less play in it now. If I like the way it looks after some tarnish, I'll do the same for all the levers/commands of my lathe. Kind of a cool way to identify where the functional parts are.
The part is turned, blasted, then turned again to get the shiny rings/bevels.

 

[drs23]

Nice job, looks good. Keep us posted.

 

[wrmiller]

You're as bad as I am, in that you no sooner get a new machine and you have to make a modification to it to 'make it yours'. I love it. :thumbsup:

 

[tino_ale]

First project that kinda want to show off... a brass Top!
Got it spinning for 6 min on a glass plate

Got a cheap knurler off eBay, but I'm amazed how well it works on brass