Great Dane excavating co.

[Lil Giants]

What bore diameters?

Why not double O rings on pistons?

[Cooper]

Originally Posted by Lil Giants

What bore diameters?

Why not double O rings on pistons?

Lift cylinders are .805” calculations are @ 300psi 153# pushing and 130# pull

@ 250 psi it’s 127# and 108#. Now that is the theoretical force from cylinders not the actual force at tip of bucket teeth. Shooting for it to be able to lift whatever heavy object that fits in bucket. 👍🏼👍🏼

I just decided to use one o-ring on pistons because I don’t see the need for 2. I haven’t had many hydraulic problems on past built cylinders. I do have two seals in the rod/cylinder head. One more so a dust seal. Tollarances are +.001” larger diameter for rod to pass through. And these cylinders don’t really have the dynamic side loads to keep rod and cylinder in line. And on the steering and lift cylinders the single O-ring gives me that little bit more travel. I’m trying to have lift arms go a bit higher than the 1:1 machines to have dumped bucket clear sideboards on the haul truck. They will but have the room so just some insurance I guess 😜. And like I said I’m using seamless tube that will be honed and polished internally. The rod is ground tight tolerance stock.

[Cooper]

P.s. those numbers are per cylinder. (One)

[Lil Giants]

Originally Posted by Cooper

P.s. those numbers are per cylinder. (One)

Yeah, I can do basic math.

So let's figure out the negative leverage ratio to determine how much lifting power you'll have at the bucket's cutting edge.

What's the distance from the hinge point at the rear of the arms to where the cyls connect on the arm?

And what's the distance from cyl's connection on the arm to the bucket's cutting edge (bucket horizontal)?

[Zabco]

How do you determine the size of your O-rings?

[Cooper]

I use 1/16” orings. Actual size of .063” ring is .070. I cut .063 groove and size off of Inside diameters or outside diameter. Depending on tube or rod. Tube is measured by outside diameter , pipe is measured by inside diameter. I’ve found if you try and compress orings too much they are too tight for a low pressure hydraulic system like we have. Say I have a cylinder rod of .25 I will usually use a oring of .25 inner diameter. And account for the actual size of oring to be the compression. And the groove is the static part the rod is the seal part. I’ll try and find some info I found a while back for you.

[Zabco]

Originally Posted by Cooper

I use 1/16” orings. Actual size of .063” ring is .070. I cut .063 groove and size off of Inside diameters or outside diameter. Depending on tube or rod. Tube is measured by outside diameter , pipe is measured by inside diameter. I’ve found if you try and compress orings too much they are too tight for a low pressure hydraulic system like we have. Say I have a cylinder rod of .25 I will usually use a oring of .25 inner diameter. And account for the actual size of oring to be the compression. And the groove is the static part the rod is the seal part. I’ll try and find some info I found a while back for you.

Thank you very much, great information. I've never done hydraulics before but have started on a project that will require me to fabricate my own cylinders as what I need to stay reasonably to scale is not available. I knew that O-rings were made to standardized sizes but no idea how to figure out how much compression was needed to make them work properly. Have you ever tried X or quatro rings? From what I've read on them they can be used as direct replacements for O-rings as they are the same size and could provide a better seal at lower compression or pressure.

[Cooper]

This is similar to what I reference



And also by trial and error, and feel .

[Cooper]

Small ring is .063” the larger diameter ring is 1/32” .03125. I would love to use the 1/32 rings but I just can’t hold that tight of tolerance on my lathe. Would make the telescopic cylinders more scale .

[bigford]

Time for a new cnc lathe

[Cooper]

Working on getting some measurements for ya joe,

Picture dump,,







Left one was first one, right one was after I tweaked the cam a bit and better finish.





This is the front and back cover for transfer case, another part will be between them tohouse gears

[Cooper]

My birthday present, I’ve always wanted a stuffed armadillo and my parents now live in Florida so I told them to be on the lookout for a stuffed armadillo. They haven’t found one yet so the got me this one .

And st Patrick’s Day, Beth’s friend visited us with her Irish wolfhounds , so ira, ours got roolay with his own kind. This was hers saying hi to me in the shop





And some scale pics

[Cooper]

And yes I changed designs on cylinders. I did make them out of steel but then switched to brass. Several factors at play for that choice. I was using 12l14 steel (high lead content) easy to machine but I didn’t realize it doesn’t like welding or brazing temps much. And also after realizing I’m planing on having several more small pieces added to cylinders for hard lines I would run into heating up parts I don’t want to heat up. With brass I can control the temp better and block the heat transfer easier. And the hard lines will be easier to fabricate withbrass tube. But one benefit, I now have spare parts from steel for future projects !! Lol!!

[9W Monighan]

Nice update today. Glad you're getting further along.

[skeeter]

wowzers! That thing is even bigger then I thought it'd be. Seeing er next to the dumper like that really makes the reality of how mamouth a machine that is!

[modelman]

Very nice work cooper-the detail work on this machine is outstanding!! Should make a great model and probably move a lot of dirt but I'm not sure I would want to get it dirty. Oh yeah-I like the "possum on the half shell" as we call it.

[Cooper]

This is the transfer case.

[Bo Wallen]

It's not just a transfer case.....it's pure Awesomeness ! Getting closer and closer to move around on its own power.

[Hofabooz]

Hi Cooper


Looking good man looking very good.
It will soon be pushing you and the dog around under its own power.

[Cooper]

should have a esc and motor arriving soon. Have the basics of the driveline done. Still need to weld up and some more details. This is a pic of the spider being machined. Did it in the mill then remove from collet block and part off on the lathe. Rotary table would be nice but don’t have one and then setting up for a simple opp,, I’ll keep with the collet blocks for now.



And some shots of universal.