Mini Mill Gas Strut Conversion

The spring head lift doesn’t work very well with the Mini Mill and so I did a Mini Mill gas strut conversion.

The spring that lifts the head of the milling machine (Amadeal XJ12-300) has been annoying me for some time. One big issue is the force is not consistent. However, it looked like a big job and so I have ignored it and carried on with the important job of model making.

Well, having purchased a digital readout for the Z-axis of the mill it was then a case of just having to fit a gas strut at the same time to make life easy.

I did a few measurements and then went online – I ended up ordering the strut from sgs-engineering.com. I ordered this at 2pm and it arrived at 8am the next day, total cost £27 including p&p – a great service.

The strut I ordered was a GS6-15-240-280 with a force of 60N and FREE end fixings for which I chose the 10mm metal ball stud with M6x1.

First thing was to remove the old spring assist – just a few bolts and some care that it doesn′t fly off.

I drilled and tapped 6mmx1 a hole in the side of the head – note that this is high up to get the maximum distance between centres.

The lower attachment is on the fixed part of the bed, this will restrict how far you can tilt the head over. I never tilt the head and so this is just not a problem.

The part number: GS6-15-240-280 means 6mm rod diameter, 15mm main body diameter, 240mm extension and 280mm long body. This is just about ok, although it does restrict the travel slightly, the GS6-15-220-260 may be a better fit.

The rear of the mill shows the gas strut in position, took me around 30 minutes, must admit that the 60N is a tad on the low side and I may buy another strut and increase this to 100 or 120N as that would then give me a positive lift rather than a neutral, slow drop.

Also, note the orientation of the gas strut with the push rod end at the bottom and main body fixed to the top, this is to reduce the chance of swarf getting dragged into the strut and damaging the seal.

I tend to run with quite a high resistance on the z-axis and so the force supplied by the strut is just to take some of the weight (60N means it relieves the mass of the head by around 6kg, 120N would be 12kg and probably closer to the actual head mass).

Do not delay in doing this mod as it transforms the mill z-axis – get on to sgs-engineering.com.

I ordered: GS6-15-240-280 and 60N force, but would consider the GS6-15-220-260 and 120N of force – with 10mm metal ball stud M6x1 ends.