HF mini mill air spring conversion

R

RB72

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Just completed installing an air spring on my HF mini mill. I used a method I had seen on a youtube video. Basically installing the air spring using the existing bolt used for attaching the torsion spring to the head and the left rear mounting bolt used to secure the mill to the bench. That way the height of the machine was not increased. I selected a 40 lb air spring after finding out that the kit supplied by thelittlemachineshop was approx. a 36 lb spring but I had seen comments that it did not completely support the head. I made an adjustable bracket at the top so the spring attachment point could be tweaked in order to get full height extension and be able to get down to the table on the lower end. I have done some basic testing and it appears to have solved the issue with head drop. I still need to replace the rack gear bar with the longer 14" one sold by littlemachineshop so the head travel will be able to use all of the column.
I have attached a few pictures.

image.jpg image.jpg image.jpg
 
Nice install! :)

I have the LMS kit on my little mill and it seems to work fine. I do like the extra z-axis travel with the addition of that longer rack.

Bill
 
I have absolutely no head drop with LMS' air spring kit installed as directed.
 
The air spring conversion really improves the usabilty of the mill for me. I can now use the z axis fine adjustment knob without having to put upward pressure on the coarse adjustment handle. Just installed the longer rack. It's nice to be able to clamp my work when needed directly to the table without having to use 1-2-3 blocks etc to raise it up so the mill will reach it.
 
Those are just auto hatch or hood struts they are cheap for cars how much is the kit?
 
iron man said:
Those are just auto hatch or hood struts they are cheap for cars how much is the kit?
Click to expand...

Yup, look like typical gas shocks. I wonder why they call them air springs or are these different & have an actual spring inside them? I was looking into installing some on my mill. Do they make a great improvement?
 
Nice install, RB72. Put the LMS kit on mine last week. Very happy, no head drop, and more Z travel at bottom and top.

Tom
 
Doubt they have an actual spring in them. But on the little bench mill sold by HF/Griz/LMS/MM they really do help make the head movement more repeatable/predictable. When I bought my little LMS mill I was really disappointed with that rack system on the column, but after doing the conversion I was able to make some pretty precise head movements (I used my 3-axis DRO for verification).

Bill
 
I purchased the air spring from Enco for $8 or $9 bucks. Bought the ball studs from Autozone for $3 and used some aluminum I had to make the brackets. The LMS conversion kit is about $40 but it includes the extended z axis. After I purchased the extended rack from LMS my cost was about the same as the kit from LMS but I did not increase the height of my machine except for about 1 inch so I could get the extra use of the extended rack.
 
Glad I found this thread, I have seen this conversion in other threads but no explanation as to why you would do it. Now I know.
 
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