Multisplit woodsplitter wedge design, metal thickness

[muddstopper]

I am finally getting around to starting my firewood processor build but cant decide how thick of metal to use to build the 12way splitting wedge. Wedge design is similar to this one Huge Wood Splitter - 200 Ton - YouTube, but only a 4way split in the center section instead of 6way. I have 3/4x8 in plate to build the 4way with, but am considering just using 1/2 plate for the rest of the wedge. The wedge opening will be 27in wide for splitting big rounds. This means the side wedges will be about 13in long attached in the middle and the outside edges of the box. My concerns are bending the 1/2in wedges more than ripping them off the main wedge under force. (I wont be using a 110v mig for any of the welding) Using half inch steel has the advantage of being cheaper to buy, and lighter weight, and thinner means less spreading of the wood between each wedge, but will it hold up to 50tons of force in knotty wood. My thoughts are that welding the thinner wedges behind the cutting edge of the heaver 4way, so that the wood is already partially split before hitting the thinner outside wedges, that the outside wedges shouldnt see much of the force needed to start the split. Also with multiple wedges, the force is spread out over a wider area and after the initial 4way split, it should take less power for each additional split. 50 tons spread out over 12 wedges equals a little over 4 tons per wedge, but I know wood doesnt split evenly in nice round numbers. Let me hear other opinions before i buy metal and start cutting it up.

 

[BukitCase]

First off, I'm coming from a probably different perspective than some of our members - I'll turn 70 next year, and have no desire to make MORE work of a project - The guy in that video has more brawn/friends than sense IMO; loading big rounds by hand (partially), having a conveyor and then letting it dump on the ground for example...

I know my hoe mounted splitter won't be as fast, but I'll be sitting on my butt wiggling levers, and the conveyor (if I even need it for this) will be dumping into my 5 yd. dump truck, which will then drive to the wood shed and dump SLOWLY onto the conveyor, the other end of which will be at waist level so I'm not breaking my back stacking...

To your question - I've looked at quite a few multi-split designs (planning a backhoe mounted splitter eventually) and I've noticed that some designs use brute force, others consider the extra force required when you sharpen both sides of a blade equally and then try to force a piece of split wood between two of those symetrically sharpened blades - this tries to force the split wood to compress, which probably adds a few tons of required force to do.

Some of the designs I saw limited the # of splits, and outer blades ONLY had a bevel on the OUTER side so central pieces were NOT compressed on the inner side.

I agree with setting the secondary blades back - it might also be advantageous to grind them at an angle so they're not fully engaging at the same time.

Also, if you have a big enough plasma cutter to CUT bevels instead of GRINDING them, I'd consider building that part out of AR plate - it might even pay to farm that part out to a shop that has a bigger plasma. I know you'd need to preheat the pieces and use Lo Hy rod, but as you probably know, AR 400 not only has MUCH higher abrasion resistance, but it's also several TIMES the tensile strength of A36 steel and (where I live) isn't that much more $$ than mild.

As to thickness, if it's welded on both inner and outer sides to a "cage" like in the video, AND if that cage is somehow supported at the perimeter to the (hopefully stout) frame, I think the 1/2" should be fine.

Just some of my observations - my free advice is (usually) worth every penny ...Steve

 

[muddstopper]

Well, I aint 70 yet, but am planning on old age being a factor. Not only that, but I like to design things so my wife can operate them if I aint around.
Some of the things you mentioned i have already considered. While the 4way will just about have to be sharpened equaly on both side of the edge, the ring that makes up the center circle does not. Sharpening only the inside edge, and making the wedge opening wider in the back than at the front should eliminate most of the compressed wood syndrome. The knifes at the outside of the ring can be sharpened on both side since the wood should be able to spread out between the knifes. setting the ring wedges back allows the initial wood to spread somewhat before encountering the secondary ring wedges, this should also reduce compression of the wood being split. I have played with this design somewhat on my current splitter and 6way wedge. The wings wedges are only sharpened on one side, bottom wing sharp on bottom side, top wing sharp on top side. Wedge opening wider in the back than in the front. About the only time I see any compression is if I am splitting a extra large round, say 32in dia. The wings are pretty even when they start the secondary split and the compression is only at the cutting edge. This is what makes me think that having the 4way set back a couple of inches from the main wedge, and then setting the ring wedge a couple of inches back from the 4way, I shouldnt see too much, or very little compression.

I do dread cutting the bevels for the knife edge, there will be about 20ft of knife edge total, ( I havent actually added it up). My plasma isnt big enough for that kind of cut so I will be stuck using the oxy/acet torch. Placing the knifes in a jig, I can keep the cut reasonably smooth, but still see a ton of grinding in my future.

As far as type of plate to use, I will probably stick to just plain hot rolled steel. I just havent seen the wear factor other folks suggest on their splitting wedges and consider it a non issue. I am not around any big steel suppliers and anything other than plain steel is special order and must be bought in stick lenghts and gets pricey, almost double. The A36, I can weld up the edge with a hard surface rod before sharpening and it will stay sharp for years. My current wedge is 3 or 4 years old and still sharp enough to cut you if you bump it with your elbow.

 

[BukitCase]

I figured you were already aware of most, if not all I brought up - but I also know that just ONE "pearl of wisdom" a person was NOT aware of, or hadn't considered, can be well worth reading a bunch of stuff that makes you wanna say "Duh"...

Too bad you don't have better suppliers close, that'd be a pain - I have an account with the one that's about 35 miles away from me, I can order new steel today and, as long as it's over $100 (pretty much always is) they'll deliver it the next day for FREE. (Probably in part 'cause their prices seem higher than the eastern USA)

I have 'em pull up on the road (country area) and I just gently "T-bone" the truck, the guy hooks my lift straps on long hooks that receiver mount to the loader bucket, I lift up, sign the paperwork and he drives away.

Plaz - have you considered setting your plaz for scarf mode? Granted, not as big a deal if you're sticking with mild steel, but I've used my PM45 in that mode a couple times and it's pretty neat. Sorry, I meant for cutting the edges instead of all the grinding OR the A/O torch -

OK, 'nuff chatter - get to work, I can't wait to see your beast in action... Steve

 

[Big Barn]

muddstopper, I'm only a hobbyist welder and would not trust my skills for your project. However there are options......



Terry

 

[muddstopper]

muddstopper, I'm only a hobbyist welder and would not trust my skills for your project. However there are options......

View attachment 399639

Terry

If i had that option, I would forget about building a processor and jus set on the porch and watch:shocked:

 

[muddstopper]

Plaz - have you considered setting your plaz for scarf mode? Granted, not as big a deal if you're sticking with mild steel, but I've used my PM45 in that mode a couple times and it's pretty neat. Sorry, I meant for cutting the edges instead of all the grinding OR the A/O torch -
. Steve

I have the older spectrum 625, I dont think it has a scarf mode. I have used it for gouge with the right tips. I have also used it to cut thru 2in shaft material, but it wasnt pretty.

Cutting the angle needed for a wedge means needing to cleanly cut thru around 2in of steel. With proper preheat and right size tip, oxy/acet will do that pretty easy. I like to turn the metal on edge and cut toward the wide part of the plate. I get less gouges that way. To free hand, I caulk a line that I want to cut to and watch the exit of the slag, making sure I dont cross that line. One side cut, flip the piece and do the other side the same way. Still tons of grinding to do, Milling machines sure are handy tools for making wedges, to bad i dont own one.

 

[Big Barn]

I have the older spectrum 625, I dont think it has a scarf mode. I have used it for gouge with the right tips. I have also used it to cut thru 2in shaft material, but it wasnt pretty. Cutting the angle needed for a wedge means needing to cleanly cut thru around 2in of steel. With proper preheat and right size tip, oxy/acet will do that pretty easy. I like to turn the metal on edge and cut toward the wide part of the plate. I get less gouges that way. To free hand, I caulk a line that I want to cut to and watch the exit of the slag, making sure I dont cross that line. One side cut, flip the piece and do the other side the same way. Still tons of grinding to do, Milling machines sure are handy tools for making wedges, to bad i dont own one.

Maybe Steve is referring to gouging tips ? I have the Miller Extreme 625 which is probably slightly inferior to his PM 45. Bit of a toss up but I think I would use the oxy/acet and have better freehand control with the longer torch if I didn't have a milling machine.

Terry

 

[BukitCase]

Yup, gouging, scarfing, potato/tomato - maybe if I'd try only playing with 5-6 projects at a time I might make more sense - might also get one finished every so often

The PM45 cut rate in mild is down to 15 inches per minute at 1" thick - I've done slightly thicker, but man it's slow. It's only rated to 1", and even at that you're down at roughly 1/16" per second. Makes me think I shoulda gone for the PM 85 while I was still rakin' in all that overtime

Oh well, when I get to the hoe splitter project maybe I'll have the indexable carbide face mill cutter for the Grizz (who'm I kidding, of course I will )... Steve

 

[muddstopper]

I know all to well the 5 or 6 projects at a time trick. I bought the parts to restore my SA200 several months ago. got plans for a bandsaw mill on the drawing board. trying to build a knuckleboom. And nothing getting done. On the other hand,, my typing skills seem to be improving, I must be spending to much time on the old puter.