TractorByNet.com - View Single Post - Rear hydraulic on Kubotas the less expensive way

5030 · 11-10-2003, 08:45 PM

Jerry:

Actually, that particular block was machined on a CNC mill using Tungsten Carbide tooling.

The block in the picture was not milled in the true sense of the word.

Because I am a Journeyman Tool and Die maker and I own my own machine shop coupled with the fact that I pride myself on accuracy, in a prototype or one off scenario, I would grind the mating surfaces.

In a production environment, the surfaces are probably fly cut, or shell milled. Nevertheless, if you were to gage the flatness of the piece on a surface plate, using a dial indicator with the block jigged properly, you will find that it's flat and parallel most likely within 0.001 or better.

You might get lucky and find a piece of old stock lying around somewhere that you could counter bore the "O" ring grooves in. I am not saying that it's impossible. What I am saying is that for the block to be leak free and the "O" ring seal to be secure, the clamping surfaces need to be parallel. The chance of picking up an old piece of rusty steel and transforming it into a leak free block with the tools lying around in your garage is a fantasy. Then you are faced with the problem of either welding on the outlet pipes or tapping the block to accept fittings. The welding scenario in a garage type environment with the trusty buzz box or the home Hobart MIG, leaves a porosity question, with the uncertainty of leaks at high pressure a hazardous question at best. The answer would be to tap the block, but then again, the local hardware store doesn't carry the type of taps necessary to thread the holes.

I don't think too many people on this site or for that matter the general public have at their disposal the type of machinery and tooling necessary to perform that task. An angle grinder and a cheap drill press isn't going to do it.

To give you some idea of the cost of a vertical miller alone, My Bridgeport cost over $14,000.00 and that's without tooling.

I could go on for pages about fit classes, tolerances and surface finishes and parallelism, but it's not germane here.

The bottom line is, from a personal safety standpoint, in regards to high pressure hydraulics, it is always better to err on the positive side rather than the negative.

In my opinion and again, my opinion only, you would be better off in the long run to purchase the block from the dealer.

The original poster stated that he fabricated the block at his place of employment, not at home.

11-10-2003, 08:45 PM	#26 (permalink)
5030 Elite Member Join Date: Feb 2003 Location: Michigan, S.E. Monroe County Posts: 3,128	Re: Rear hydraulic on Kubotas the less expansive way Jerry: Actually, that particular block was machined on a CNC mill using Tungsten Carbide tooling. The block in the picture was not milled in the true sense of the word. Because I am a Journeyman Tool and Die maker and I own my own machine shop coupled with the fact that I pride myself on accuracy, in a prototype or one off scenario, I would grind the mating surfaces. In a production environment, the surfaces are probably fly cut, or shell milled. Nevertheless, if you were to gage the flatness of the piece on a surface plate, using a dial indicator with the block jigged properly, you will find that it's flat and parallel most likely within 0.001 or better. You might get lucky and find a piece of old stock lying around somewhere that you could counter bore the "O" ring grooves in. I am not saying that it's impossible. What I am saying is that for the block to be leak free and the "O" ring seal to be secure, the clamping surfaces need to be parallel. The chance of picking up an old piece of rusty steel and transforming it into a leak free block with the tools lying around in your garage is a fantasy. Then you are faced with the problem of either welding on the outlet pipes or tapping the block to accept fittings. The welding scenario in a garage type environment with the trusty buzz box or the home Hobart MIG, leaves a porosity question, with the uncertainty of leaks at high pressure a hazardous question at best. The answer would be to tap the block, but then again, the local hardware store doesn't carry the type of taps necessary to thread the holes. I don't think too many people on this site or for that matter the general public have at their disposal the type of machinery and tooling necessary to perform that task. An angle grinder and a cheap drill press isn't going to do it. To give you some idea of the cost of a vertical miller alone, My Bridgeport cost over $14,000.00 and that's without tooling. I could go on for pages about fit classes, tolerances and surface finishes and parallelism, but it's not germane here. The bottom line is, from a personal safety standpoint, in regards to high pressure hydraulics, it is always better to err on the positive side rather than the negative. In my opinion and again, my opinion only, you would be better off in the long run to purchase the block from the dealer. The original poster stated that he fabricated the block at his place of employment, not at home.