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EVguru
03-18-2012, 07:34 PM
Some time ago I bought a Denford Easimill 3 for a reasonable sum. It'd hoped to start playing with it straight away, but I discovered a problem. The cap that retains the quill bearings was broken.

As with many other Denford CNC products they used an existing machine and fitted it out with CNC control gear. In their wisdom they used a clamp on the end of the quill to provide the Z-axis drive. That might have been OK, if the bearing cap hadn't been made from Aluminium. Even then it might just have worked if there were more than two complete turns of thread and it wasn't machined from a slightly porous casting!

I'm not the first person to have the problem;

http://www.denfordata.com/bb/download/file.php?id=245

Picture taken from this posting; http://www.denfordata.com/bb/viewtopic.php?f=50&t=835

This weekend I finally felt up to spending some time in the workshop and starting from a rather oversize chunk of steel barstock machined up a replacement.

The first task was working out the thread. Initially I though that since this was a 1984 machine of far east origin it would be a Metric thread and had initially thought it was an 'orphan' thread of 73 by 1.5mm, but a closer look and some head scratching made it more like 2.9" by 16 TPI.

I recently put a Sinpo DRO on the Harrison L5 and this was my first experience of using a lathe so equipped. So much easier! Especially as some time in the (ex school) past the lathe had been updated to metric. However, due to the cost of a replacement telescopic cross-slide leadscrew (about 750!) only the dial had been changed which caused some confusion when I first got the machine.

After a LOT of swarf production (around 70%)

http://www.compton.vispa.com/Pictures/spindle1.jpg

and it even fits nicely with the thread done entirely by the numbers;

http://www.compton.vispa.com/Pictures/spindle2.jpg

wierdscience
03-18-2012, 09:39 PM
Looks good,has to be better than the pot metal original.

Toolguy
03-18-2012, 09:50 PM
Great job! It should run for years!:)

EVguru
03-19-2012, 09:41 AM
Thanks for the comments.

Now I have to decide what to do about the Z-axis drive. I could just put it all back as it was, but it strikes me as badly lacking in rigidity. I'm tempted to use the knee as the Z-axis and fix the quill in the (most rigid) up position.

Toolguy
03-19-2012, 10:20 AM
If you have a quill clamp you can use that to secure the quill for CNC work, but unclamp to use like a drill press if you just want to drill a hole or 2. The knee is really the better Z axis if you can make it work that way.

EVguru
03-19-2012, 11:12 AM
If you have a quill clamp you can use that to secure the quill for CNC work, but unclamp to use like a drill press if you just want to drill a hole or 2. The knee is really the better Z axis if you can make it work that way.

If you slacken off the quill clamp plate, the quill will fall out! :eek:

Denford did not bolt a conversion kit to an existing mill. They bought in part machined castings and built the machine up their way. There's no rack cut into the quill and the head casing was not machined to fit any drive/quill lock.

I thought about driving the quill via the depth stop block like many Bridgeport conversions do (it's only used for the limit switches at the moment), but the knee conversion is looking better and better at this stage.