mini mill gas strut

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miner49r said:
Swede,
Maybe I wasn't clear. That is not my website. I copied the cable lift from RysiuM. I'm sure he would be flattered by your compliments.
Alan

Hey Alan...

Do you have pictures of your version? I am curious to know how it works as well? Did you use the same gas springs?

Eric
 
Eric,
Pictures are forthcoming. I have the mill torn down for mantenance. Should be back together tonight. Tram .
tomorrow.
Alan

As Promissed. My clone of the Rysium Compound Cable Lift.

b1.JPG


b2.JPG


b3.JPG


b4.JPG
 
Thanks!

I like that design. I think I am going to try to imitate it? I saw that rysium used gas springs with six inches of travel. Is that what you used? Do you find it limiting? Also, did you make your pulleys?

Eric
 
two ropes holding the weight means 6 inches of ram travel will be doubled to 12 inches of head travel.

Tom R
 
tomrux said:
two ropes holding the weight means 6 inches of ram travel will be doubled to 12 inches of head travel.

Tom R

Derp! You are correct. Wasn't thinking about that.
 
Your installation is looking really good. To me this brings up a question, So if you have two struts @ 55 #'s, even with the weight cut in half by the travel, will that be too much for the head since it only weighs 30#s? I am asking because I found a 50# strut with a 14" strokeat a local surplus store and was wondering if it was too much.
I also mounted my rack so that it sticks up about 3" above the column. It really does make a difference when trying to install 1/2" drill bits above the vice and work.
 
Eric,
With the Z-rack extended above the column the head has a full 12" of travel. The gas springs I used have a seven inch travel allowing me to be preload them. You can see the 3/8" eye bolt and threaded coupler I used for loading the springs.
My original thoughts were to use to dual rate springs when RysiuM showed me his setup. The gas springs made it a "no brainer". As RysiuM mentioned in his notes, there is a slight delay in the gas springs where the cable goes slack. (it is slight, yet noticeable) Maybe a combination of springs and gas springs would overcome this.
Alan
 
Tech100,
There is quite a bit of lifting force. The #55 struts were salvaged from an old truck tool box and were my favorite price. Is a positive lift better than a floating balanced head? I don't have the answer to that. At this point "head drop" is no longer a worry. Your milage may vary.
Alan
 
I was wondering the same thing. I suspect part of the issue is how they rate them. Is it's analagous to a spring, one would think it must be a function of their compressed % or position? Maybe maximum?

I would thing you would want the head it 'almost balanced' so it still wants to come down on its own but still makes for easy up-cranking assist within the typical range of the head, no? Floating up like a balloon after releasing the locks would be weird. :D

Here is some sizing/terminology info I found, maybe helpful.

http://www.mcmaster.com/#about-gas-struts/=guo2ju
 
The rate of pressure rise is proportional to the square of the diameter ratios (for a quick and dirty calculation).

For a 10mm rod, 22mm bore gas strut this wil be (10/22)^2 = 0.206

or a 20% increace in force over its stroke (guestimate).

More correctly for a proper V1 / V2 calculation if you start with a volume of 1.00 then less the 0.206 rod volume entering = 0.794

1 / 0.794 = 1.259 or 26% increace in pressure

ie :- 1 / ( 1 - {[d/D]^2})

Normally there is a small quantity of oil for wetting and lubrication which will not significantly affect this - but some applications contain a lot of oil either as an end of stroke damper or to deliberately ramp up this rate.
Some are made with a large redundant volume (the rod is a lot shorter than the tube) to reduce the rate.

Ken
 
Thanks Simon,
The credit really goes to RysiuM at the GrizHFMininill group. If I had to change anything I would put #40 struts instead of the #55 ones. I would have to buy them.
Alan
 
I just received my air spring kit from LMS and am about to install. I read somewhere while researching this mod that the LMS instructions where incorrect as far as where to drill the hole for the lower end of the strut. But, now I can not find that post again.
Can anybody shed any light on this before I go ahead and drill the hole?
 
That's the one I was looking for, thank you.
Good news is that they must have updated the instructions. The ones I received say to place the hole 15" down from the top, which is much closer to your number than the 12" figure they gave You.

Thanks again for your reply.
 
I had emailed them back when I made that post. Nice to see they are paying attention. That kind of customer service is what keeps me buying from them.
 
I know this post is old but I would like to ask Alan if he finds the stronger springs better for drilling operations?
 

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