Using a Rockwell tester

I recently bought this low-use Togoshi Seiki Rockwell hardness tester (photos in this folder on my website):

http://www.eurospares.com/graphics/metalwork/hardnesstester/

Anything that looks like rust is just a thick coating of LPS3 smeared over the metal.

It didn't include any documents. I found some generic instructions for another brand of tester on the Web and I think I'm clear on which sets of weights to use but that's about it.

There is a conical point in it now and a very small ball in a tube in the case, as well as a couple of test blocks. The point looks to be in good condition.

How do I use this? I'm guessing that I put the appropriate number of weights on the back (all three for Rockwell C), pull that lever on the top right forward, raise the knee pressing the point against the part until the small arrow points to the small red dot on the left of the dial, zero the dial to the "set" point, and then trip the lever to release the weight. Whatever number the needle points to when it stops moving is the hardness. Is that right?

If the needle doesn't match the rating on the test block, what do I adjust? There are some threaded shafts on that thing (hydraulic dash pot?) on the left side of the column, but I don't want to fiddle with them without being clear on what they are supposed to do.

FWIW, I paid $400 for this. They seem pricey and this is from a Japanese firm so did I get a decent deal?

thanks,
Michael

After you trip the lever, and it stops, pull that lever back to thr original position, and reading should be correct. Only tamper with any linkage adjustments as a last resort.

IMHO, you got an excellent deal on the tester.

Micheal,
Your sequence is a little off.The top right lever should be in the most clockwise position (up) before you start a test.

Make sure the correct weight stack is on and correct point in place for the appropriate scale.

place part on anvil
crank part into point(be careful at contact)and continue to crank until needle reaches straight up (90%) position.
zero dial on needle(fine tune)
release crank and allow it to move on its own until it stops
turn crank back up (clockwise) and observe reading
compare to what test block says it should be
congratulate yourself if you did everything right

On my wilson testers, the weight lever rotates forward (CCW) to remove the weight load. Whichever way yours removes the load from the penetrator is the correct position to start in. The conical point is called a Brale penetrator. Protect the point, it's a diamond and can be damaged by striking it with a workpiece.

You have it correct on the beginning of a test, zeroing the dial. Make sure your sample will not move as the weight is applied and then removed, both for accuracy and to protect the penetrator. Once it's at zero, release the weight with the lever and allow the penetrator to, well, penetrate the workpiece until it stops. Then lift the weights with the lever, and read the dial. You want only the initial loadm not the penetration load, on the penetrator when you read the dial, so that you are only reading how far the penetrator penetrated under load, not the spring and flex of the tester frame, etc. The dial is just a calibrated dial indicator, each .00080 of penetration equals one point of hardness. There is a procedure to balance out the tester's mechanism. I have a description of it for my Wilson testers, it might apply to yours, if you need it I can get a copy of it to you. If you test several test blocks of different hardnesses and it varies significantly from block to block, it may need that adjustment. The dash pot is just to slow down the penetrator dropping, should not need adjustment as long as there's enough oil in it. If it's low, put some 10W in it.

i paid $700-$750 for my testers in much wors cosmetic condition, I'd say you did good.

Here's a good hardness conversion chart - http://www.carbidedepot.com/formulas-hardness.htm

There are others around the web. You'll also want a chart to correct for test specimens with curved top surfaces(round bars) etc.

http://www.public.iastate.edu/~e_m.327/equipment/instructions/rockwell.pdf

are the instructions for a somewhat similar machine. That mentions aligning the small needle and dot like you can see in the photo of the dial on my machine. The "set" or zero mark can be in any location as the number ring rotates..

The instruction I was missing was pulling the lever back up before reading the dial. The 63C test piece seems to come out right on the money once I add that to the sequence of operations.

I grabbed a few things to test. A Honda motorcycle primary pinion gear is HRC 60. A case-hardened 8620 aftermarket motorcycle adjustable cam sprocket (Kawasaki Z1 by APE) is HRC 55. A stock Honda vintage cam sprocket (CB160) which didn't seem very hard registered HRC 11 so I'm presuming that's a steel without any heat treat (matweb says annealed 4140 is HRC 13 and cold drawn 1018 doesn't get hard enough to use the HRC scale).

Do those test numbers sound reasonable?

I was surprised by the stock cam sprocket being so low but I guess a 30T 219H sprocket running in a constant oil mist/bath might have a fairly easy time on a little streetbike and not wear very quickly. The stock cam and valve springs don't put a very big load on the cam chain. The Z1 sprocket (same chain size) would have a more strenuous life with 2X as many lobes and potentially drag race types of lifts and valve spring pressures, so the case hardening probably helps prolong its life span.

It seems like it might be feasible to use 4140HT (HRC 26-32) for an upgraded cam sprocket on the little Honda twin vintage roadracers. I bought the APE sprockets to check out and they'd work on the 160 cams with a new carrier being made to match them but they'd have to be modified on ID and adjusting screw slot location for 175/200 camshafts.

Thanks for the help!

cheers,
Michael

A stock Honda vintage cam sprocket (CB160) which didn't seem very hard registered HRC 11 so I'm presuming that's a steel without any heat treat (matweb says annealed 4140 is HRC 13 and cold drawn 1018 doesn't get hard enough to use the HRC scale).

Do those test numbers sound reasonable?

Click to expand...

Depends where on the sprocket you tested. Parts like that are often induction or flame hardened so that only the teeth get hardened. That leaves the main body of the sprocket untouched so that it is easy to work with later and also does not distort. The next dilemma is how to test the teeth - They might be case hardened which requires a superficial type rockwell tester which uses much lighter test loads so as to avoid penetrating through the case depth and registering an incorrect result, and they may be so small as to not be structurally strong enough to stand up to the Rc test load without distorting which also causes an incorrect result. Try touching the tooth area with a file and see if it feels different than the center hole.

Otherwise your numbers are right on. When testing your test blocks, test one side only because dimples on the bottom will return incorrect readings when they flatten out. If you test it 4 times and get different readings each time, that can be because the material in the block is not completely homogeneous and therefore they are slightly different hardness in different spots.

John, the first test on the stock sprocket was 8.5mm in from the root of the teeth. I did another one just under 4mm from the teeth and it came out pretty much the same (HRC 10). Anything closer to the teeth and the sprocket wouldn't stay flat on the table.

The lathe turning pattern is visible on the sides of the teeth where they were tapered in and it took about 8 light strokes with a fine file on the side of a tooth to take that pattern off. It doesn't seem very hard. Since the 160 uses the same sprocket/chain size as a Z1 but with only about 5mm of stock valve lift (the high lift race cams give 7mm lift) and full lift spring pressures around 90 pounds/valve it may not be a very high stress part that justifies an extra manufacturing operation to harden the teeth. Only Honda knows what they were thinking 40 years ago.

cheers,
Michael

Flammability Tester

Mud said:

Depends where on the sprocket you tested. Parts like that are often induction or flame hardened so that only the teeth get hardened. That leaves the main body of the sprocket untouched so that it is easy to work with later and also does not distort. The next dilemma is how to test the teeth - They might be case hardened which requires a superficial type rockwell tester which uses much lighter test loads so as to avoid penetrating through the case depth and registering an incorrect result, and they may be so small as to not be structurally strong enough to stand up to the Rc test load without distorting which also causes an incorrect result. Try touching the tooth area with a file and see if it feels different than the center hole.

Otherwise your numbers are right on. When testing your test blocks, test one side only because dimples on the bottom will return incorrect readings when they flatten out. If you test it 4 times and get different readings each time, that can be because the material in the block is not completely homogeneous and therefore they are slightly different hardness in different spots.

Click to expand...

And maybe the Flammability Tester can help you a lot, which can determine the degree of flammability on the basis of the flammability test results after a variety of materials are tested under different conditions.