Another homemade splitter...

Do you have a pressure relief valve in the system? I would think you would want to stop the ram if the pressure rose to a point that it could damage the splitter as what happened in this case; also keeps you from getting hurt if something fails and throws towards you.

 

The valve has a pressure relief built in I believe.

 

Don't believe, know for sure. You sheared grade 8 bolts and bent the beam; if there was a pressure relief valve it either failed or was at too high a pressure. Be safe OK?

 

Actually, I just checked the valve I ordered and the max setting is 2000 PSI:

PRINCE MONOBLOCK VALVE
Brand new PRINCE. For control of cylinders, motors, etc. Open center, built-in relief valve. Pressure-release detent adjustable from 1,000 to 2,000 Psi.

SPECIFICATIONS•25 GPM
•Adj relief valve
•Pressure operated detent on return stroke, spring center on extend
•IN/OUT 3/4" NPT
•Work ports 1/2" NPT
•Size 9-1/4" x 5" x 3"
•Shpg. 11 lb.

 

I am not a mechanical engineer; I just had a few courses in such things. Hopefully someone knowledgeable will come in and talk about this as it is important for your safety in your wood splitter. Also, see if you can contact someone at the company about the valve. Go over your plumbing as well. It would appear that the ram might have stopped; pressure rapidly built up until the pressure was relieved by shearing the bolts and bending the beam and that it happened quickly without any warning.

 

To me, that is a little on the light side and honestly angle iron is weak by design for what you are trying to do. A T or box design in steel will always out perform an angle because you get more flex or distortion from an angle. Nothing supporting one side so it pushes away. I'm no engineer and degreeless but I've built enough things to see what can happen. This is why it threw red flags to me prior.

 

I am a degreed engineer; that's why it broke!

If you look closely at the beam design, it is boxed. I think my biggest problem was using the Northern Supply cylinder mount. For an I-beam it's probably fine but in my case I was bolting at the weakest part of the beam.

If I weld some 4" wide, half inch thick strips....


...around 10" long with additional holes closer to the outer edges of the angle....


...and then have a 12" x 10" mating plate underneath that would "sandwich" the top leg of the angle, I think my problem will be solved. My nephew is putting together a pressure gage from work to test and set all the pressures just to be sure. I think if I set everything at 2250PSI I can get an honest 22 tons safely out of it.

 

Let us know how it does.

 

Of course!

 

Glad to meet another engineer; my degree was electrical but we had to have some cross training so had classes in statics and dynamics.

I was curious about the grade 8 bolt failing and found this on a forum:

Henry:
What is the shear strength of grade 8 bolts 1/4″ – 1″

Call accepted by Dane McKinnon. Currently in room: Dane McKinnon, Henry.

Dane McKinnon:
Good afternoon Henry. Shear strength is typically 60% of tensile strength, and the minimum tensile strength of a grade 8 bolt is 150,000 psi. We have an FAQ that addresses this question here: http://www.portlandbolt.com/technical/faqs/bolt-shear-strength-considerations

Henry:
How are all grade 8 bolts the same tensile strength?

Dane McKinnon:
They are all the same tensile strength per square inch. The larger ones have a larger cross section of material, and so are therefore stronger. To calculate the tensile strength of a particular size, you would multiply 150,000 psi by the tensile stress area, found here: Thread Pitch Chart - Portland Bolt

Henry:
Thank you

 

Yah, I'm actually a draftsman by trade, Mechanical Design Engineer by years of night school (Springfield Technical Community College for my Associates and U-Mass, Amherst for my Bachelors), manager of the Design Engineering department at my company for 10+ years and now I work as a Project Manager in PDI (Product Development and Innovation; R&D to the rest of the world). January 2nd was my 26th anniversary with the company!

Yah, those Grade 8's should take a lot of force to shear them. The beam must have buckled first and then broke the bolts as I continued to use it without realizing what happened. In retrospect, I probably did not forget to tighten them, but I may have actually over-torqued them. I tightened and removed them several times during the build, tear-down, and painting.

 

Please ensure your welds are getting full penetration, I see a few areas that have spaces between start/stop.

 

Nowhere in the above did I claim to be a welder!
The picture above I did with my old stick welder... My welding skills have improved since getting my MIG, but yes, point is taken!

 

It's all good.

 

True, high torqued bolts are often not meant to be reused; although I have on my axle without failure. Did you find the bolt so you could examine it to see how it failed?

was going to include a table but there is no html edit.

 

Yes. One bolt was missing but 4 of the others were still in the bracket. I saved them but have not looked at them too closely yet; maybe I'll take some pictures tonight if I get a chance.

I bought some steel at lunch. Picked through the drops near the shear. Found two 8" x 8" x 1/2" thick plates and two other 12" long 1/2" thick pieces; one is 3 1/2" wide and the other is 3" wide. Charged me $10 which I thought was fair.

Going to my brother-in-law's machine shop after work to drill holes in the plates. 1/2" holes through 1/2" plate is much easier on one of his Bridgeports than my drill press at home!

 

Yes, I miss my machinist friend; who also had an BSEE. He use to help me a lot; machined a piece of aluminium and then bore though the center and then tapped threads to match a threaded rod; I used it to press out cam bearings and then install cam bearings in a head for a job I did on my sister's Honda. Saved me from having to buy the tool to do it with or pay a machine shop to do it for me. I designed it with a shoulder and cut to width of the bearings. It would automatically stop when the bearing was fully seated. I had never installed cam bearings before that job and it went smooth as silk.

 

I made the additions to the cylinder mount. I ground 45° chamfers 1/8" deep on both sides where the welds would be. I think I got some real good penetration that way:

I welded both sides of the joint carefully to minimize warpage. I stitched the top, then flipped it over, stitched the bottom, flipped again, etc. until it was fully welded:

Then I ground everything smooth. This is the finished mount (minus paint):


I took the 8" square drops and cut sections, beveled and welded like above to end up with a plate that is 10½" wide x 11¾" long (front to back) to use as my plate under the beam. I didn't take any pictures of it yet. I still need to drill the last holes in it. I may run a "keel" as ljohnsaw mentioned but only for the length of the backer plate. I haven't done the calculations, but spreading the load like this I think is sufficient with or without the keel.

 

I have another question, this one on hydraulics. The valve on my splitter that controls the cylinder is an open center, detent retract valve. This one in particular:
1 SPOOL PRINCE HCSVG0002/LS3000 LOG SPLITTER VALVE

The valve I used for my hoist was brand new and given to me. The guy bought it for his splitter but it didn't have the detent return so he bought a different one. I only looked up the specs today (I know, poor engineering) and it says it's a 10 GPM rated valve (I'm running a 22GPM pump) and it's listed as a "closed center". This is the valve:
Energy 20038 Directional Control Valve, 1/2" NPTF, 2500 psig Buy from Cross
My plumbing starts at the pump, goes to the hoist valve, then to the cylinder valve, and then back to the tank. I'm thinking the hoist valve may be limiting my flow to the cylinder valve and therefore the cylinder itself. Can someone smarter than me confirm/deny this?