[jduke]

I got a used dm4400m a few weeks ago and am planning a retrofit to new motors and controls.

My first sticking point was the spindle that I got with the machine was not the original it may have been a DM part, but it was not mounted, and also was not complete.

It is missing the drawbar entirely. So with no drawbar, and the proprietary pull system that dyna had missing I decided not to try to fix this spindle.

Several bt30 spindles are available on AliExpress at tremendously different prices.

I ordered one that is 90mm in diameter and a little shorter in height than the original also has a different bolt pattern than the original.

Now I will need to make a spacer to fill the 2.5mm radius. And drill and tap new mounting holes in the Z casting.

Fortunately at least 30mm of the drive pulley is above the casting so the height should be Okay.

At this point my plan is to take the Z casting off the machine and use my Lagun mill to drill and tap the holes.

I have a piece of pipe that’s about the right size to make the spacer, I can fine tune it on my lathe and hopefully get a good press fit.

I considered boring the head out and using a bigger spindle but I think BT30 is a good fit for this machine

Duke

[jduke]

So I bought a piece of metal tubing that was pretty close to the correct dimensions and used my shop fox 1099 lathe to dimension the inside of the tubing to 90mm then when turning the outside I left it a few hundredths past 95mm

I had to use my 12t press to get the sleeve into the Z axis upon measuring it appears that pressing the sleeve into the cast iron compressed it slightly so I went through multiple cylinder hones trying to increase the internal measurement from 89.75 up to 89.95mm then I pressed the spindle in using the same 12t press. then I drilled and tapped the cast iron for the mounting bolts and the spindle appears to be pretty solidly in place.

the tool changer ram isn't long enough, so I am going to have to make an adapter to extend its reach.

there is a hole in the middle of the tool changer ram that appears to be for air to come through and as the tool changer ram retracts to its topmost position it presses what appears to be an air valve to blow air through the center of the tool changer ram.

What is the purpose of blowing air through as it returns to top position?

thanks Duke

[mactec54]

So I bought a piece of metal tubing that was pretty close to the correct dimensions and used my shop fox 1099 lathe to dimension the inside of the tubing to 90mm then when turning the outside I left it a few hundredths past 95mm

I had to use my 12t press to get the sleeve into the Z axis upon measuring it appears that pressing the sleeve into the cast iron compressed it slightly so I went through multiple cylinder hones trying to increase the internal measurement from 89.75 up to 89.95mm then I pressed the spindle in using the same 12t press. then I drilled and tapped the cast iron for the mounting bolts and the spindle appears to be pretty solidly in place.

the tool changer ram isn't long enough, so I am going to have to make an adapter to extend its reach.

there is a hole in the middle of the tool changer ram that appears to be for air to come through and as the tool changer ram retracts to its topmost position it presses what appears to be an air valve to blow air through the center of the tool changer ram.

What is the purpose of blowing air through as it returns to top position?

thanks Duke

Making the sleeve was a waste of time as it is not needed

The spindle on a CNC machine normally has clearance and are quite a loose fit in the main housing, they are aligned by the flange so need clearance

There is always an air blast to help clear any chip in the spindle before a tool is inserted when doing a auto tool change this is a timed air blast

[jduke]

Making the sleeve was a waste of time as it is not needed

The spindle on a CNC machine normally has clearance and are quite a loose fit in the main housing, they are aligned by the flange so need clearance

There is always an air blast to help clear any chip in the spindle before a tool is inserted when doing a auto tool change this is a timed air blast

Thanks for the input on the air blast, it makes sense.

The spindle I was replacing did not have to be pressed out, but it did require percussive persuasion to get part of the old 95mm diameter spindle out.

I don’t doubt that I went overboard making it a true press fit.
I was shooting for a slip fit, but my measurements weren’t as accurate as they probably should have been on the sleeve.

I still find it hard to believe that leaving a full 2.5mm gap all around the new 90mm spindle would have been adequate.

I can’t imagine that the face of the spindle casing would be as good at supporting work load at the end of a bit, as having the full spindle body supported in a sleeve.

Thanks for the input, I don’t think I’ll press it out and redo it at this point, if I start having trouble with the bit being angled or bearing life appears to be effected, I’ll look at making another sleeve with more focus on the slip fit.

This is for my home shop, so I doubt either of those will be effected enough for me to spend the effort.

Thanks
Duke

[mactec54]

Thanks for the input on the air blast, it makes sense.

The spindle I was replacing did not have to be pressed out, but it did require percussive persuasion to get part of the old 95mm diameter spindle out.

I don’t doubt that I went overboard making it a true press fit.
I was shooting for a slip fit, but my measurements weren’t as accurate as they probably should have been on the sleeve.

I still find it hard to believe that leaving a full 2.5mm gap all around the new 90mm spindle would have been adequate.

I can’t imagine that the face of the spindle casing would be as good at supporting work load at the end of a bit, as having the full spindle body supported in a sleeve.

Thanks for the input, I don’t think I’ll press it out and redo it at this point, if I start having trouble with the bit being angled or bearing life appears to be effected, I’ll look at making another sleeve with more focus on the slip fit.

This is for my home shop, so I doubt either of those will be effected enough for me to spend the effort.

Thanks
Duke

Yes the biggest problem you will have is how to tram the spindle now you won't have the clearance to do it, if you where concerned with the gap you could of just used a spacer sleeve at the top of the spindle