Thread: RF45 Gas Struts?

Has anyone here put gas struts on their RF45/46 size mill to counterbalance the head?
If you have, I’d be interested in some pictures of how you did it, and some feedback on whether or not it’s worth the effort.

Thanks

I have seen it done a fair few times over the years since someone invented it back then.

I would go for struts with enough push to lift just under the weight of the head, so it helps it and doesn't actually push it up, creating backlash on your screw.
Keeping some weight on the screw will eliminate it

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I’ve attached a few photos of gas struts I installed on my CNC’d HM-48. I worked out where the mounting points needed to be by considering the maximum extent of the table towards the column, the total Z-axis movement, length and diameter of available struts, and clearance around the gib locks and Z-axis DRO scale. I had to make new longer gib lock bolts, but otherwise all went fairly smoothly.

Hard to say how necessary it was. I installed the struts as a precautionary measure at the same time as I converted the machine to CNC, in case issues arose with missing steps when raising the head, however I think the Z-stepper (Nema 34) probably has more than enough power to work okay without them, since it seems to be able to move the head even with the gibs locked! Also I wonder whether the head might be more stable without the struts, with its weight ‘locking’ it better against the column.

Thanks for the pictures and the feedback, much appreciated.
Like most decisions, I’ll probably procrastinate on it a bit longer.

Are gas struts your preferred option?

Have you looked at others?
Just wondering,....

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They seem to be a relatively popular modification amongst the youtube crowd, haven’t seen or thought of any other viable options that are as simple as struts. Counterbalance on the head of one of those machines certainly seems to make sense, was just wondering if it was worth the effort or not. I had a pair of 700N struts that are about the right length fall into my lap last week which was what prompted the question.

Originally Posted by racingtadpole

Has anyone here put gas struts on their RF45/46 size mill to counterbalance the head?
If you have, I’d be interested in some pictures of how you did it, and some feedback on whether or not it’s worth the effort.

Thanks

Not a RF45, but similar. Was it worth it? Absolutely was for me, but if I was still in my 30s I probably would not have thought to do it.

Very easy mod and makes life easier.

RF-30 struts 2.jpgRF-30 struts 1.jpgRF-30 struts 3.jpg

That's enough to talk me into it... I'll add it to the list of things to fix/alter/change when its in bits in a few weeks time.

Thanks for the pictures, much appreciated. You have 300N struts on your 30 size machine, the head of a 45 is marginally heavier being gear driven, I am wondering if the 700N ones I have on hand might be a bit on the heavy side.

If there mount is the standard one and they are standard length as ones being sold, give them a try, then if you find there too strong they would be easy enough to change out.

Most used one's loose some of their strength over time.

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Originally Posted by racingtadpole

......... You have 300N struts on your 30 size machine, the head of a 45 is marginally heavier being gear driven, I am wondering if the 700N ones I have on hand might be a bit on the heavy side.

I would think so. I have never seen a 45, so the head might be slightly bigger, the gears might be 5-10kg so even if the difference is 15kg, you would still only need 350N-400N max each side.
Mine is very nicely biased with just a few kgs of down-force on the rack & pinion.
You certainly wouldn't want any upward force on it.

EDIT: They were only $24 for the pair. (evilbay)