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View Full Version : Reducing the stroke of a 150mm x 800mm hydraulic ram to 550mm



simonl
12th Dec 2016, 08:51 PM
Hi all,

I mentioned some time back that I was planning to build a hydraulic log splitter. It's one of those projects that, while I can live without it, it will come in handy. It also allows me to make use of some stock that I have had laying around for around 15 years, waiting for a suitable project.

Some time back I starting looking for the key components, a ram, a suitable engine, hydraulics and a hydraulic pump. By far the hardest to find (within a budget) was a suitable sized ram. Strictly speaking, a perfect size ram would have been a 5" with an 18 - 24" stroke in good condition. Very difficult to find especially close to home since freight is also a cost consideration.

So, when a 150mm x 800mm ram was found on ebay, in what appeared to be in very good condition, I ummed and arred for a while because it was obviously too long and too big in diameter. It was also in NSW. I did some ringing around and through Truckit I got a quote of $80 for delivery (it weighed over 100Kg according to seller) and managed to haggle the price to $250, so I bought it. Initially I decided to just keep the ram as is and work around the extra size. I only plan on plitting logs of maybe 450mm long or so. Then, looking at the construction, it occured to me that I may get away with reducing the stroke by literally cutting it down. I quick google search revealed that some people have done a similar operation but it's not common. The ram in question is a Vickers W40 series. Detailed documentation on these rams is readily available on the net.

Reduction of the ram involved three main parts. Cut the tube (cylinder) to correct length, cut the rod and re-machine a new thread for the clevis attachment and cutting and re-threading the 4 rods. A saw a couple of issues that may have brought me unstuck, the length of the tube and ram and fitting it on my 12x36 lathe and the fact that the rod was Chrome plated and induction hardened. I read conflicting stories from people machining chrome plated, induction hardened rams. I figured I'd have a go.

Easiest part, cutting the cylinder in the bandsaw. As the blade passed through I realised I'd passed the point of no return, I may have been creating scrap metal! The length was measured to allow the thickness of the piston allowing a new stroke of 550mm.

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Next, I had to find a way to face off the newly cut end to ensure it was square. I also had to incorporate a chamfer to facilitate the sliding of the O-ring seal during re-assembly. With an OD of 180mm, it was never going to fit in fixed steady. I found an old flywheel from a small honda motor (I replaced it with electric start which required replacement of the flywheel) I turned the flywheel down between centres so it would fit snuggly inside the cylinder. I don't have any measurement equipment other than a vernier for this size so it was trial and error, cut, test, cut test etc. Turning between centres using the initial bore made it pretty straight forward. I then added 3 small grub screws that would take up once inside the cylinder, just incase it had a tendency to slide from the pressure of the live centre. In reality, they weren't needed as it was a snug fit but the thought of a 700mm, 20Kg cylinder coming loose as speed also did not excite me!

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The cylinder machined very nicely. It also turned out that using a steady to face the cylinder would not have worked out as well because it was noticeable that the wall thickness was not even. Using the ID of the cylinder produced noticable runout on the outside. While not at big issue when facing something this long, but it would have affected the chamfer.

The finished face on the right, in comparison the factory machined cut off part on the left. I was happy with that.

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Next up was the rod. Before I put it in the bandsaw and hope for the best, I tested it was a file. Needless to say, it just laughed at the file, not even a mark. So I measure the required length and cut the circumference about 5mm deep with a thin blade cutoff wheel in the angle grinder. I then put it in the bandsaw and had no real issues.

I then proceeded to put it in the lathe and turn between centres and this was when I became majorly unstuck. It was too long! Beggar. A new plan. The piston end had a protrution of the rod of about 30mm. I decided to turn a piece of scrap delrin, OD to push fit in the centre of the face plate, ID to be a push fit on that protruding shaft past the piston. This registered the piston end concentric. I then clamped the piston up against the faceplate. Now, the other end needed supporting. If I could get a centre drill in the end then I had justy enough room for the TS with a dead centre, but not enough room of a live centre. The fixed steady did not adjust all the way to fit the 3" rod BUT by disassembly of the parts, I was able to shim the rod until it was at centre height (using a DTI) and then nipping up the grub screws in the steady. It only had to run for 10 seconds until I centre drilled it. It worked.

The ram originally had a 2-1/4" thread, but for my use I figured a 50mm thread would be fine. This would also allow me to use the cut off part of the rod to make a matching female thread and then weld on a clevis arrangement. The first 3mm of machining was hard going. I really gave the TCT tool something to think about. There were sparks, I'm not too embarissed to say. If my lathe was bigger I probably would have gotten away with cutting under the chrome plate in one pass but I just didn't have the rigidity to do this and so my cutting tool was punished. Once I got through the chrome plate, the induction hardening was evident until I got to about 3mm and then it machine nicely.

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When it came to machining the thread, I decided to have a go at using indexable 16 ER 60 inserts instead of my usual home sharpened HSS tools. I was just keen to give it a go. Well, to my surprise they worked a treat. They cut beautifully and I even gave up using the compound at 29.5 deg. for tool advancement. I just plunged the tool with the cross slide at about 0.2mm (0.1mm DOC) increments and got very nice results. I will be making a matching female part, but in order to test fit the female part, I decided to make another separate M50 x 2 test part out of one end of the discarded rod. Much easier to test fit a 200mm part than the actual rod. I also used thread wires to make sure I was right in the zone with the pitch diameter, that was another first for me.

The next part was to cut the threaded rods to the new required length and then re-thread the ends. The rod measured pretty much spot on 25.4mm, 1" and so cutting thread was pretty straight forward. While they were not super hard, then were obviously not MS. Maybe 1045 or 4140. They could be filed. I measured the pitch and noted they were 14 tpi. I assume a standard UNF thread but when I looked up my threads, standard UNF is 12 tpi. It turns out that this thread is called several things. 1" UNS or just simply 1"-14 UNF. I also needed to new nuts at the flange end. They were a stock item and cost all of $2.50 each. I thought that was pretty cheap!

Cutting the new thread was pretty straight forward, I even used the same insert for the M50 x 2 thread since unified threads a 60 deg anyway. I then made an easy job unnecesarliy more complex when I realised that I didn't thread the rod long enough. The thread took up before the cylinder was pulled tight! I had to put the rod back in the 4 jaw, centre it and then match up the tool with the existing thread and cut another 5mm of thread.Certainly not even close to being impossible but I was annoyed at myself! Being new to threading with inserts, I was a bit sceptical of the finish using a lathe like mine. So I took a 10x pic with a loupe. The thread finish is pretty good.

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Last part was to trim some edges off the flange at the end of the ram. The flange is designed to be bolted using the 4 x 2 slots on the sides. I don't need these as I intend to use the threaded rods. The threaded rods thread through the flange and I cut them to extend beyond, to allow to be passed through a bulkhead plate on the log splitter beam. The 4 extra nuts I bought will fix it to this.

last thing to do was clean up the parts, give it a re-spray and reassemble...

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Cheers,

Simon

KBs PensNmore
12th Dec 2016, 09:33 PM
Thanks for that Simon, a very interesting how to. The first 2 pics don't work I get an Invalid Attachment specified. If you followed a valid link, please notify the administrator (http://metalworkforums.com/sendmessage.php), I don't know if it's my computer or something else.
Kryn

simonl
12th Dec 2016, 10:15 PM
Thanks for that Simon, a very interesting how to. The first 2 pics don't work I get an Invalid Attachment specified. If you followed a valid link, please notify the administrator (http://metalworkforums.com/sendmessage.php), I don't know if it's my computer or something else.
Kryn

Hi Kryn,

Not sure what went wrong. I re-attached those pics and it now seems to work.

Simon

KBs PensNmore
13th Dec 2016, 12:22 AM
Thanks for fixing that. You've a nice sized bandsaw, what's the maximum size that can be cut in it? Looks like it makes my 6X4 a toy.
Kryn

Michael G
13th Dec 2016, 06:33 AM
Simon's thread on his bandsaw - http://metalworkforums.com/f65/t175836-re-birth-heska-260-ha-horizontal

Michael

simonl
13th Dec 2016, 07:07 AM
Thanks for fixing that. You've a nice sized bandsaw, what's the maximum size that can be cut in it? Looks like it makes my 6X4 a toy.
Kryn

Your 6x4 is not a toy. Many people do lots of work using the 6x4. Michael beat me to it (Thanks Michael) my BS started out as pretty much a boat anchor. I think it would have ended up as scrap if I didn't buy it. It now serves me really well. It will fit a 400mm wide stock and 260mm high (at 90 deg). It plays up from time to time. I have replaced the hydraulic seals a few times and have since re-machined (skimmed) the idler wheel so it runs flat and true again and the blade stays in place.

Thanks

Simon

Oldneweng
13th Dec 2016, 11:16 AM
Very nice work Simon. The 3" diameter rod surprised me. I have a 5" ram and the rod is way smaller. Some clever outside the square thinking. I recently machined a 65mm pin. My steady would not quite close down that far so I started to think of simple ways to overcome this problem. I finally thought to undo the locking screws so the shafts could travel past the keyway end and that worked.

Dean

simonl
13th Dec 2016, 04:48 PM
Very nice work Simon. The 3" diameter rod surprised me. I have a 5" ram and the rod is way smaller. Some clever outside the square thinking. I recently machined a 65mm pin. My steady would not quite close down that far so I started to think of simple ways to overcome this problem. I finally thought to undo the locking screws so the shafts could travel past the keyway end and that worked.

Dean

Hi Dean, yes the 3" rod is way heavy than it needs to be for my use. That's why I was happy to reduce the thread to 50mm. I looked at other commercial log splitters and many only had a 2 or 2.5" shaft. What you explained with your steady is exactly what I did, you just explained it better!

Simon

snapatap
13th Dec 2016, 05:12 PM
The 1"-14 thread is commonly referred to as 1" SAE. It is reasonably common, i have encountered it on a lot of older mining equipment, hence the cheap nuts.

KBs PensNmore
15th Dec 2016, 12:03 AM
I know my 6X4 isn't a toy, (I've cut a 300 mm long piece of cast in it), but by size comparison, it is. I think the reason for the 3" shaft, is to do with the tonnage of the hydraulics in a pushing situation. anything smaller could bend.
Kryn

simonl
17th Dec 2016, 09:08 PM
Hi all,

thanks so much for your comments and feedback. Snap, it does appear that this thread has several names. The local bolt shop where I bought these nuts showed me the box that they came in, it was labeled 1"-14 UNF.

Hi Kryn, looking at the Hyteco_ Eaton W40 cylinder catalogue, this came in three shaft sizes 2.5", 3" and 4" shafts. The 2.5" being standard the 3" being heavy duty and the 4" being extra heavy duty.

While I look at the figures, I also find it interesting that with a 6" cylinder driven at 3000 psi, the force yielded is about 38.4 Tonne. Yet when you look at hydraulic log splitters sold online and at machinery shops they quote 50 Tonne force with a 5" ram and 3000 psi. My sister and Bros. in law recently bought a reputable brand splitter with a honda motor etc. and it has a claimed 50 tonne ram force and it also has a 5" ram and the pump is quoted at running at 3000 psi. The figures don't add up. Also my ram, has maximum rated pressure of 2900 psi yet is built way heavier than any log splitter cylinder I have seen.

Simon

KBs PensNmore
17th Dec 2016, 09:35 PM
The Cylinder on the families log splitter, probably came from OS and they could have a strange way of doing their maths. The reseller is probably quoting facts and figures from the catalogue of the manufacturer. A bit like getting 3 HP from 500 watt electric motor???I would tend to believe info from the Eaton catalogue.
Kryn

franco
18th Dec 2016, 01:05 AM
The Cylinder on the families log splitter, probably came from OS and they could have a strange way of doing their maths.
Kryn

Some strange tons indeed!

As a rough check I make the 6" cylinder @ 3000 psi about 38.5 metric tonnes, or 42.4 short tons or 37.8 long tons,
and the 5" cylinder @ 3000 psi about 26.7 metric tonnes, or 29.4 short tons or 26.3 long tons unless I am missing something. On those figures the Eaton catalogue figure which is presumably in metric tonnes would be the about right. I would be interested to see how they arrived at those ratings for the 5" cylinders.

Frank.

Michael G
18th Dec 2016, 08:08 AM
There are losses involved from seal and piston friction - typically we would see these at 5 to 10% of the available force near maximum operating pressure. We had an efficiency requirement that we had to meet and found that while we could test at lower pressures, the frictional forces were 'constant', so gave us a test failure.
In reality, the available force will be the calculated force (P/A) less 5 to 10% and then rounded down to a neat number.

Michael

simonl
18th Dec 2016, 08:29 AM
Hi Michael, Thanks for that. I had no idea that there would be such relatively high losses from the seals. It does make sense though as when I was assembling the cylinder, it took a huge effort to push the piston back in the cylinder. I certainly couldn't do it using my own body weight pushing down. It is quite a tight fit.

Here's an example of a log splitter that claims to be 60 tonne, yet it has a 6" ram and a pump pressure of 3500 psi. Do the maths and that equates to just under 45 tonne.

60 ton DIESEL ELECTRIC START ENGINE HYDRAULIC LOG SPLITTER WOOD FIREWOOD | eBay (http://www.ebay.com.au/itm/60-ton-DIESEL-ELECTRIC-START-ENGINE-HYDRAULIC-LOG-SPLITTER-WOOD-FIREWOOD-/331177831062?hash=item4d1bbcaa96:g:otgAAOSwAuZX6Gda)

I mean who really needs 60 tonne to split wood anyway. Seems like a big part of marketing these things is to quote ridiculous force figures. In reality, 25 tonne is probably all you really need. I notice the big commercial firewood processors only quote around 28 tonne for their machines.

Simon