help surgery needed milling machine

hi my mill xj12 need summ fairlky serious repairs the split nut for the table leadscrew thread has gone and ruined my job also the table end plates are so worn on the lead screw theres 2 mm movement in the hand wheel

now the problem being i cant get spares for it iv tried so need to make sum bushes and a new split nut but how do you measure the thread of the leadscrew? its not a thread iv come across in the scense off the thread is flat no points to the threads so not sure on that one could some one please explain how i go about this

many thanks mike

Have you tried Amadeal for spares ?

hi john yh iv tried its were i got the mill from and normally use him but in this case he dosent do this part

Try Chester machine tools and ask for spares for the Century mill, same model as the XJ12.

Tell them whether it's a metric machine or imperial machine as the nuts are different.

Hi Mike,
To find the pitch or the thread you do not need to take any measurements. Look at the graduations on the handwheel and work out how much the table moves for one revolution handwheel. That distance is the pitch of the thread. The thread is known as an acme thread
Have a look at this web page.

Les.

HI michael
I sounds like a square form thread to me . simililar to threads used on Drummond lathes. Check The diameter and then you can check the pitch counting the spaces say over about 2" if its a acme thread they would be angles on the flanks
Nobby

To further muddy the waters there is not much made nowadays using square threads, too hard to cut on automated machines.

Acme thread if imperial or trapezoidal if metric is the way manufacturing has gone because these can be rolled easily and fast.

Acme has an angle of 14.5 or 29 degree's included.

Trapezoidal has an angle of 15 degrees or 30 degrees included.

John S.

hi les if i have done this correct im not sure i have per rev of my hand wheel graduations it works out to b 1.5mm movement so a lil bit confused but it is a fine thread so could be right the dia is 5/8 or would the dia be a metric size being that its a metric machine it

it sure does look like an acme thread

its measureing 15.78mm od and with a table movement of 1.5mm per rev of hand wheel

.

Edited By michael burton 1 on 05/11/2012 23:03:17

Hi Mike,
1.5 mm pitch sounds about right. (The X axis lead screw on my Sieg X3 is 2 mm pitch) It is possible that your mill is the same as either a Seig X1 or X2. If you do some investigation on the internet and you find it is the same as an X1 or X2 then this should help you to find an alternative supplier. Also consider making the nut out of acetal plastic. Look at this LINK.

Les

hi les i like that link might give that method ago looks simple enough

I have a XJ25 mill from Amadeal (pretty crap mill). I have made new screw nuts for both axis on my mill. The thread is M16 x 1.5mm pitch. The thread form is conventional 60 degree metric form and not flat topped. The Y axis is obviously left hand. I bought the taps from Tracy tools and used lumps of bronze to make the nuts.