Dial graduations versus feedscrew lead.

A friend has just purchased an Osaki mini milling machine from Cromwell Tools.

It looks similar to the ones offered by Machine Mart and Arceurotrade etc, but I was surprised to find the handwheels are graduated to 0.75mm per rev , which in itself is somewhat odd, so when I went on to confirm this via the rule(r) mounted on the front of the machine, I was even more surprised to see that one turn of the handwheel resulted in 1.5mm of table travel

Does anybody have an explanation for this?

I might add that a complaint has been made to the supplier and they state that all their machines are the same and so can't fit more appropriate handwheels. They are however, willing to collect and refund his payment.

Martin.

Upon reading the Instruction Manual (on Cromwell site) it is supplied with a "fuselage" and that you need "cake" to attach an item to the table. All Chinglish of course

Only one reasonable thing comes to my mind: Some lathes has cross slide handwheel/thimble graduted to show progress in DIAMETER. I can't be sure which brand it was but I'm pretty sure I saw least one long time ago.

Could it be possible, that maker had copied this consept to lathe and oneday they had surplus of lathe handles and they were wheeled to a half ready batch milling machines?

Then again it could be any combination of hanwheels/lead of the feed screw and metric/imperial concotion combined with one digit error on order code.

I have seen handles "calibrated" with 0-100 readings with aproximate mm/" markking, neither of them was accurate, even tough feed screw had nice 3 mm/r lead.

Pekka

KWIL.

At a push, with a good wind behind me, I could just about go with 'fuselage' to describe the body of the machine. On the other hand, 'cake' makes me wonder what the author had on his mind at the time of writing.

Pekka.

I've got a lathe with a cross feed dial like that, but that's actually opposite to the situation on the milling machine, because the lathe dial is graduated 5mm per turn coupled with a 2.5mm pitch feedscrew.

Martin.

Just a though since this do seem to be a strange machine, have you checked that the 1.5mm indicated table movement is actually 1.5mm?

Jim

Kwil

My machine (seig version) has 75 graduations of 0.02mm and 1.5mm of feed per turn of the handwheel and is clearly marked as such.

Are you assuming that the 75 graduations are 0-.01mm each?

60 graduations would be a much better choice for both metric and imperial work.

Joey

Sounds like the 0.02mm is ok to me

Pultra 1590s did 100 graduations on a 2mm leadscrew

0.02mm a pop

I just read the pdf for this machine, I just love reading chinglish, it's so much better than the telly.

there is one thing that looks very useful tho, under cutter maintainance is says " wrong rotating direction may cause sharpness".

looks like they are on to something there, instant tool sharpener!!!!

Roy.

Joey,

Not me, I did not comment upon the divisions in any way. Merely the Chinglish Manual.

KWIL

I decided to contact Arceurotrade to find out about their equivalent machine.

I have been told that the feedscrews fitted to the Arceurotrade machine are of 2mm pitch and the dials have 80 divisions, so that equates to 0.025mm per division, which is quite understandable to me because it's also pretty close to 0.001". So a good compromise for metric vs imperial when getting down to finished size.

Martin.

My Axminster (Sieg) mill has 75 0.02mm graduations on x and y axis handwheel and 60 0.025 graduations on z, 1.5mm per revolution in all cases. It is confusing having a different scale on the z axis but must be Chinese logic. My machine also has a fuselage, Chinglish for column I believe.

Ian.

Just been thinking about this again...

I take it that the Arceurotrade 80 div dials and 2mm pitch feedscrews are graduated as something like:-

12 O'clock = 0/2mm, 3 O'clock = 0.5mm, 6 O'clock = 1mm and 9 O'clock = 1.75mm, rather than just numbered from 1 to 80.

Anyone know for sure which way they've done it?

Martin.