Log splitter design....

[Tractor Dave]

Hi everyone,
I'm thinking about making a vertical log splitter for my dissertation at uni, i've looked at many designs and all seem to have a similar set up with respect to the slider connecting the blade to the vertical steel section.
Here is a pic of what i'm talking about:

http://www.mpearsengineering.co.uk/pages/compactimp.htm

I would have thought with the cylinder being offset, it would have had the tendancy of jaring the leading edge of the slider, especially considering the force which is being applied. Am I missing something ie is there something between the slider and vertical steel section or is there a better design?
Any help or words of advice would be greatly recieved!
Many thanks
Tractor Dave.

 

[Paul.]

A polyethylene block as a wear plate is a simple and usual method with slow moving machinery, also polytetraflouroethylene (PTFE) is commonly used but probably not worth the expense on a log splitter.

 

[wyn]

I suppose it's all down to cost.

A real expensive way might be to use rollers. Or maybe use an engineering plastic.

Is the "jamming" more likely to occur when the blade is not in contact with the log.

 

[Tractor Dave]

Cheers, I think the plastic route would be better as its cheaper and quicker, although roller would be more proffesional....
I'm planning on designing a rotating table, so might use rollers in that!
Cheers for the advice, i'll up date you how its going!
Dave.

 

[Tractor Dave]

Is the "jamming" more likely to occur when the blade is not in contact with the log.

I'd have thought the jamming would occur whilst not in contact like you say as the log will level the blade up....i think!
Also, does anyone know what hydraulic pressure a classic tractor (1964 era) work at???
Dave

 

[wyn]

Maybe if the ram was substantial enough, instead of connecting the top with a pin, it could be more of welded/bolted sort of connection. This could get rid of the need for the slide/brace as it looks like it is only there to prevent the ram from moving out of the vertical position....if that makes any sense.

Maybe the slide is a bit of a crossover from horizontal designs.

 

[Tractor Dave]

Ey, thats a grand idea, why didn't I think of that?? Have to be pritty substantial mind as the forces invloved and if the surface of the log is not level, as the blade will tend to tilt....
Dave

 

[Paul.]

If you restrain the body of the cylinder, everything else has to be perfectly aligned, as if there is any side load on the piston rod it will wear the piston seals prematurely, better to fix at each end as per the one in the photo, and let the cylinder float,

 

[bob the builder]

It looks to me that the ram is much to far forward on that machine, when I made my own splitter I used 100mm box and then made a box to fit around that to use as the slider works great, I power mine from the hammer lines on my mini digger.

 

[Tractor Dave]

Also i suppose the blade will flex if there isn't a slide, especially on max stroke.
Bob: Is your slider and 100mm box metal to metal contact?

 

[Pete.]

Perhaps if the table had a slight dish in it the log would always tend to roll directly under the ram, reducing the chance of putting torsional forces on the connection and reducing the load on the sliding joint on the column.

Also to me the one in the pic looks set too high - the biggest log that could be split is the width of the cutting blade so the clearance below need not be much more than that. Dropping the assembly a few inches toward the table would effectively increase rigidity.

 

[Tractor Dave]

Perhaps if the table had a slight dish in it the log would always tend to roll directly under the ram, reducing the chance of putting torsional forces on the connection and reducing the load on the sliding joint on the column.

Also to me the one in the pic looks set too high - the biggest log that could be split is the width of the cutting blade so the clearance below need not be much more than that. Dropping the assembly a few inches toward the table would effectively increase rigidity.

I think the dished idea is good in principle, but if the log is not the "normal" log shape or weighted to one side, this could prove a problem?
I'm all for making the structure as ridgid as possible and build alot of strength into it, im designing it to take logs that are 2ft in dia and 8" deep, so it'll be pritty substantial!

 

[bob the builder]

You must use a slide, and yes mine is metal to metal a little grease and there is no friction attall, you will find you can split logs of large diameter because you split from the edge and not the centre of the log. The log height is important 8 inchs is not enough.

 

[Sam]

I run my one metal to metal think there was about 0.5 mm clearence also put a couple of grease nipples and a few groves on the slide to hold grease has been working fine the last 6yrs. Also welded on a piece of angle either side of the blade to give a secondary split which helped.

 

[snowcat]

Also, does anyone know what hydraulic pressure a classic tractor (1964 era) work at???
Dave

around 2300psi, depends on the machine, fords were not great with there hydrulics....i assume you must be running a spool block on an open return then, to get a double acting supply.......

 

[Tractor Dave]

I see, so what sort of height would you reckon on? Although I suppose it depends how you cross-cut the tree!
That looks like a grand blade Sam, i've got myself the front edge of a bucket, just need to put another angle on it, certainly heavy enough! I might add some angle if needed, but the blade is pritty wide as it is!
Cheers Snowcat, i can finally do my calculations, i'm planning to run it using my International B414, which luckily came with a return coupling (not seen many Internationals with them fitted)!
Do any of your log splitters have any safety features or hydraulic relief valves etc?
Thanks for the help guys, much appreciated!
Dave

 

[snowcat]

buy a complete spool block, with a relief incorporated, you should have one on externally operated equipment, you can put a gauge on the line or on the test port and set you crack off pressure then independently on commission, I was going to suggest a bit of beveled hardox but it sounds like thats what you have for the cutting edge, don't forget your preheat and plenty of legs on the welds when you weld it together, you can get doubled beveled hardox btw...... you might see an off-cut lying around some ware

 

[Sam]

Yes my one does if it hurts let it go quickly!

I set the blade back from the end stop plate a wrist thickness also on the brigs and stratton 4.5 hp motor I can split a log with the motor running just above tickover, but when I split large rounds I split them as if I were doing it by hand starting at the edge and working your way in.
One other thing you may consider is a dog leg either side so if the log gets stuck when you draw the ram back to home it will push the log off the blade.

 

[Tractor Dave]

I'll try to buy a complete block, but the place i was planning on buying the hydraulics seem to sell everything seperatly and being on a budget as i'm paying for my dissertation myself.... I'll keep my eyes peeled at work, amazing what you find in the skip or tossed to one side!
The dog leg sounds like a good idea, hopefully wont be needed much if the blade works!
Blimy, just seen the prices of relief valves, bit on the steep side!! Looks like i'll be working weekends!

 

[snowcat]

look for a scraped hedge cutter or like, you shouldn't need to buy new there the sort of things that survive on scrapped kit, it doesn't matter if its got too many services they can be shortened buying a ready made block will be much cheaper than all the bits........might be worth giving Ray Larrington a phone 01205 280304, he might have a S/H block about.......