Midas 1220 XL longitude “nut” worn.

[mac1911]

Part 1. I have been trying to get this
1220 XL to a better place.
This is my first lathe and I paid short money for it and overall have not invested much money to the machine it self. So its a very good learning experience for future lathes.
I have slowly resurrected this lathe from something that spins to something somewhat usable.

Today Im moving on to the lead screw nut or as Smithy calls it
Longitudinal Nut: Which is NLA
No longer Available . Parts are drying up for the Midas line.

When power feeding this nut will skip

The “nut” is no longer available.
The “nut” does not seem overly complicated to make. My problem is test fitting the part. I know I will disrupt the thread tool engagement if I have to remove the part from the lathe. Ideally a 2nd lathe would be better. I will post a few pictures and videos soon and up date post.

Part 2. Here is one pic of the set up.

 

[markba633csi]

One idea would be to make a short piece of surrogate leadscrew so you wouldn't have to remove the part to test fit

Why the nut is skipping? Is it because the leadscrew is deflecting or is it something with the nut mechanism?
Or maybe a bit of both? One improvement you could make would be adding a fixed "shoe" to press against the screw opposite the nut
that would slide along with the carriage

 

[mac1911]

One idea would be to make a short piece of surrogate leadscrew so you wouldn't have to remove the part to test fit

Why the nut is skipping? Is it because the leadscrew is deflecting or is it something with the nut mechanism?
Or maybe a bit of both? One improvement you could make would be adding a fixed "shoe" to press against the screw opposite the nut
that would slide along with the carriage

Pictures and video will help , ran out of time

 

[Tincamp67]

I have not had my Smithy apart, but I’m surprised it’s only half a nut. I know my south bend has a split nut that cams together. This seems like a poor cost saver for Smithy.

 

[mac1911]

I think im going to try the loctite thread repair for the time being. Then work on some sort of traditional half nut retrofit?

 

[Tincamp67]

I looked at my machine and it has a full brass block, threaded right through. If I can remember tomorrow, I’ll take a picture. It’s not an elaborate thing, but it also has a lever to snug it in place. Might be something you could duplicate or modify for your use.

when I called Smithy about parts several years ago, they were unable to pin down the model and said it was either an AT300 or Midas 1220.

 

[mac1911]

Old Smithy Machine Identification

Cutting Threads: All the feed screws on this machine are in a metric thread pitch. When cutting threads, be sure to use threading chart on the inside of the pulley box door on your AT300. Threading charts you may see in more recent machine manuals are likely different. Ordering Parts and...

smithy.com

 

[mac1911]

I looked at my machine and it has a full brass block, threaded right through. If I can remember tomorrow, I’ll take a picture. It’s not an elaborate thing, but it also has a lever to snug it in place. Might be something you could duplicate or modify for your use.

when I called Smithy about parts several years ago, they were unable to pin down the model and said it was either an AT300 or Midas 1220.

I had a good call with them trying to figure out a solution.
The best they ended up telling me is it is a “inch” or 10 TPI thread.

What they could not tell me is the actual type of thread.

 

[mac1911]

For the time being this will have to do. JB weld and Brownells release agent. How well it will hold up?
I dont put a lot of hours on the machine. 30 hours over the fair weather months on average.
Next possible step is to recreate the part in “plastic” “melting” the threads into it. Then fabricating a way to mount the other half of the nut for a true half nut? Will see. Right now I have a few parts to make for a old lawn mower and snow blower project.

 

[OTmachine]

For the time being this will have to do. JB weld and Brownells release agent. How well it will hold up?
I dont put a lot of hours on the machine. 30 hours over the fair weather months on average.
Next possible step is to recreate the part in “plastic” “melting” the threads into it. Then fabricating a way to mount the other half of the nut for a true half nut? Will see. Right now I have a few parts to make for a old lawn mower and snow blower project.

Make the piece out of delrin with the bore sized at pitch diameter. Cut piece along bore centerline. Heat the screw to about 500 deg F. . Clamp the delrin to the hot screw to form the threads. Machine outside true to new threads.