What is the pitch/tpi for fp2 X axis leadscrews in Imperial and Metric?

I have a new 400mm X axis leadscrew for sale on *bay. However, I am not 100% sure if it is metric or Imperial. It is 10 tpi which is close enough to 2.5mm pitch that I am not sure I can measure the difference with calipers. So first hope is that Deckel used something other than 2.5mm pitch on the metric version of this screw. Can anyone confirm one way or the other?

Dave

whats the od

Dave:
Inch screw is indeed 10 TPI .1" per rev on the dial. But you knew that.....

Should be able to to see the difference by going 10 or 20 threads and measure the distance edge to edge....
at 10 threads the difference between inch and meter screw would be around .o16"

If in doubt put the screw on the table of your FP2 laying in a "T" slot use an indicator in the machines spindle to read the side of a thread at a given height on the screw in question....
Move 10 turns and check the same spot on the screw...if the indicator reads "0" you have an inch screw....if the test thread is short by about .016" the screw is metric.

You can carry this out further....Lay a good 6" rule along the screw in question....at 6" the Inch screw will index exactly... edge of one thread to the same side of the 60th thread down the screw...
The meter screw's 60th thread will fall almost .1" short...easily seen by eye...

Pretty sure they used pitches that are pretty much equal to each other...makes the feeds come out the same without needing different gearing...
Cheers Ross

Thanks Ross, you're right, it should be quite visible. I checked with a good steel rule and at 13" there was no visible offset. So its an Imperial leadscrew.

stonehaven, it is about .940" - .942" diameter (measured over the threads it was .940", measured just beyond the threads it was .942")

Metric is 4mm pitch so yours is defenitly inch
I know as I have one made right now at a specialized shop
Price is about half that of one from Singer Probbably not as accurate but with a DRO it does not need to be IMHO

Peter from Holland

I'm pretty sure that the X lead-screw on my metric 1965 FP2 is 24 mm x 4 mm, meaning 4mm advance per rotation. (That's pretty different than 10 TPI, which would be a hair more than 2.5 mm advance per rotation!). On my machine the dial has graduations of 0.025mm, so there are 160 divisions around the dial. These days I hardly look at it anymore, just at the DRO.

peterve said:

Metric is 4mm pitch so yours is defenitely inch

Click to expand...

Dave,
I am pretty sure that Peter is correct with about 10 turns to the inch on an imperial screw.

In preparation to moving to a Condo in May, Markus Fulmer got all my catalogs and manuals at NAMES in April together with other non Deckel stuff.
Sorry not to be of more help.

Arno

Arno:
Greetings...nice to see you here....Hope all is well with you.

Have never owned nor run a metric Deckel....interesting about the difference in the screws.
Now it would seem to me that an inch machine if fitted with a DRO would more easily handle tight tolerance work owing
to the "slower" screw making the handwheel movement less radical...so in effect easier to execute small moves....

Also when working off the dials, the inch version has only 100 divisions per rev...so more space between the marks...and perhaps
easier to split the spacing.....Guess it is what you get used to, but to me looks like the inch version has the advantage on small close moves...
Cheers Ross

Hi Ross,

AlfaGTA said:

Now it would seem to me that an inch machine if fitted with a DRO would more easily handle tight tolerance work owing
to the "slower" screw making the handwheel movement less radical.

Click to expand...

I think that's right. The inch version has marks spaced at 0.001" and metric has marks spaced at 0.025 mm. These distances are very close to each other. BUT the inch version has only 100 marks around the dial, whereas the metric one has 160 marks. So it's easier to make fine moves on the inch version.

I am not sure about this, but I think I may have seen some more recent metric Deckels where the dial spacings were 0.01 mm, so about 0.0004". Could someone comment, is that right?

Cheers,
Bruce