V-blocks, what size?

[joea99]

This may be the wrong place to ask, but, since it relates to hydraulic cylinder work . . .

Probably going to end up doing a few more cylinder re seals. I'd like to check the rod straightness in a more certain manner than the straight edge and feeler gauge method. I have dial indicator and stand, but no v blocks.

Being a seat of the pants mechanic I'm only guessiong what size I need, The rods are 1 1/2 and 1 3/4. Doubt I will ever do any cylinders that have larger rods. So, is a 1" wide V sufficient?

 

[oldnslo]

I would believe 1 inch wide would work. Are you planning on rotating the rod on the V blocks to check for run out or placing the rod on the blocks, check height. Rotate 90 degrees recheck height, etc. if constant rotation bigger blocks might have less tendency to make the rod climb on the edges.

 

[Root Cause]

Just ignore me if you have this all thought out but without knowing more, I would ask how you will keep the V blocks and indicator in place while you hold and spin the pins. Your indicator tip doesn't have to be dead center but you will a false reading if it is moving. Same for the V blocks.


Honestly, if I were going to do this, I would make 2 V blocks out of wood and add 2 roller bearings on each one with a shoulder bolt to keep them in place.

Then screw the V blocks to a piece of 2 x 6 piece of wood however long you like. Now everything is clamped or screwed to a table and you have both hands free to spin the pin. Amazon has crazy cheap bearings and I think this would be cheaper and easier to use. Just my 2 cents. Good luck

 

[4570Man]

I would file this in the if it ain’t broke don’t fix it category. If it doesn’t flop when you roll it on a flat surface it’s good enough.

 

[KWentling]

Having made quite a few new rods for cylinders from purchased new materials (comes in 20' sticks), I can assure
you that even new ones aren't perfectly straight, and don't need to be. Rolling it on a flat surface is good enough.

 

[pmsmechanic]

I'll post this just to show how much you can get away with. I noticed my steering cylinder was bent on my 4410. I don't know how much because I never measured it but it was enough I could see it by looking at it. I left it installed on the tractor with the cylinder fully extended. I then used a piece of wood and a metal bar to straighten it out. The rod doesn't look bent and it doesn't leak so that's good enough for me.

 

[ruffdog]

It is better to be bigger with the v-blocks than too small. You don't need hardened and ground blocks for what you are doing either. Get a pair of machined cast iron v-blocks with a 2"+ V in them and it will work great. You should be able to get the rod well within .01" TIR.

 

[jmc]

If my trig is right, a 1.4" diameter shaft or larger will perch up on the 1" V's edges rather than nesting down between the V's flats. Probably accurate enough, judging from other posters' comments. Might be an issue if you straighten the shaft using the V blocks for support, due to limited surface contact.