Grinding Shims.

Many Thanks Gentlemen, yet again I'm impressed with the breadth of knowledge here. I should perhaps explain my concerns...
When I bought the wreck that used to be a 500/4[so seized it wouldn't even push down the road],I decided to embark on a philosophy of intending that this machine should last another 25 years. This meant replacing everything that would have experienced wear and so couldn't last another lifetime.
This includes :pistons,valves, both engine chains,clutch,exhaust,brake discs,entire braking system except fot the callipers and master cylinder bodies,handlebar switches, carb rebuild kits,all bearings,chain+sprockets,rear shocks[got some origional z900 replacements],tyres,battery,ignition system,rec/reg,and a few more bits:blink: :woohoo:
I also built a new wiring harness.
Ultimate recycling!
Painted the frame[after stripping it by hand:unsure: ]
I bought a Ultrasonic cleaner:woohoo: :woohoo: :woohoo:
Loads of tools etc.
So, a labour of love,[my last love legged it shortly after the bike arrived],but what the hell,you gotta do it. right?:woohoo:
So I need to get it right first time[gasket sets $120 ea],and where better to find out how but here?
So the cost is now in the thousands:silly: and I'm trying VERY hard not to screw upB)
So Thanks again Guys, you are the Best.
Piccys soon, I know you like them.

If you are going to make shims, make them out of 8720 and case them .020 deep. Then grind them to size on a surface grinder.

Has anyone done a hardness test on a shim? I have an ultrasonic with a diamond stylus for inspecting harness on harndened bushings at work, I'll bring a shim in and find out just how hard they are. Turning a particular steel alloy with the right tool geometry may sufficently work harden the surface. Again I will have to look into this. In a well set up turning operation I believe the proper parallelicity can be maintained and the shim can be sized to the .0001" on my lathe at home. A CNC with live tooling a bar feed headstock could turn out hundreds in a hour, probably in the $2 a shim range. In the numbers these were manufactured in the process was probably very specicific to the part, not a gerneral machining process by any means. But for Joe Shmoe at home, a more simplified process may result in a usable shim, at low cost of coarse.

A CNC with live tooling a bar feed headstock could turn out hundreds in a hour, probably in the $2 a shim range.

Anyone have a CNC?? I know I'd be willing to pay $4 a pop for these. Hell I'm sure you could talk to Jeff at Z1 and have a retailer to sell them for you to. Just my $0.02.

Tyler wrote:

Again I will have to look into this. In a well set up turning operation I believe the proper parallelicity can be maintained and the shim can be sized to the .0001" on my lathe at home.

You can face, on a lathe at home, to be parallel to within 2.5 microns? My hat's off to you! I'm impressed when I do it on my surface grinder.

Since the shim is a wear surface (for the shim on top motors), You probably ought to take surface finish into consideration.

Did you read the post by APE Jay up above? I don't know whether you are aware of this or not, but APE Jay is the owner of APE. And he has a really nice shop, and does this kind of stuff for a living, so I'm inclined to listen closely when he says how to do something (wish he would tell me what his honing process is, but he won't ).

Give it a shot and see though, you never know until you try

I wouldn't even think about making these without using a surface grinder to take them to thickness. Even if your tool height is perfect you are going to have a change in diminsion towards the center of the part because your sfm is so slow. Constant surface speed on a cnc helps with this. Nothing I have faced and parted off in the lathe has had perfectly parallel surfaces when taken to the surface grinder.

APE Jay wrote:

If you are going to make shims, make them out of 8720 and case them .020 deep. Then grind them to size on a surface grinder.

Correction... 8620

8620 is pretty soft and is made for corrosion resistance if I'm not mistaken...

.23 carbon, high nickel, high chromium.

I'm wondering if a higher carbon, higher silicate steel without high chromium but maybe a little bit of nickel would suit better?


APE Jay wrote:

APE Jay wrote:

If you are going to make shims, make them out of 8720 and case them .020 deep. Then grind them to size on a surface grinder.

Correction... 8620

Guys understand I am just thinking out loud here. Of coarse a surface grinder will produce a very accurate part, my pondering is if it is really needed for this type of application. Like I said above I can turn a small part to within a tenth or so and I would venture that would be accurate enough for a shim. Its not about making a comerical quality part, it is a question if a home machinist can make his old bike run... and since my project had an extra "loaner" engine in it I just may try and see what happens... I simple test run could answer alot of questions like if the bucket or valve stem show wear, of if the clearences stay stable or not. But for now I am just thinking out loud.

8620 is a case hardening material. It can be cases to have high surface hardness with a softer core to prevent cracking. Just what you want for shims.

Jay

APE Jay wrote:

8620 is a case hardening material. It can be cases to have high surface hardness with a softer core to prevent cracking. Just what you want for shims.

Jay

I'll have to get my hands on some of this. The closest modern equivalent to an ancient samurai sword would be 1050 to 1095 with 1070 being the most common, so these grades along with 02 or A2 end up in everything I do.


Tyler wrote:

Guys understand I am just thinking out loud here. Of coarse a surface grinder will produce a very accurate part, my pondering is if it is really needed for this type of application. Like I said above I can turn a small part to within a tenth or so and I would venture that would be accurate enough for a shim. Its not about making a comerical quality part, it is a question if a home machinist can make his old bike run... and since my project had an extra "loaner" engine in it I just may try and see what happens... I simple test run could answer alot of questions like if the bucket or valve stem show wear, of if the clearences stay stable or not. But for now I am just thinking out loud.

I think at 10k+ RPMs you wouldn't want this shim 'rocking' back and forth..

I just wonder what the tolerances really need to be. Now that I think of it a preferable design would be to have rounded valvestem top and a dish on the botton side of the shim. The result would only require one precision surface be ground, but this would assume the bucket would keep the shim in alignment with the valve, and keep in contact with the valve. The truth is the bucket may float off the shim at high rpms so that might not be the best idea in that regards....


Still I am going to try test the hardness of a factoy shim tomorrow.