Housing specs, question for other machinists
 

The specs that I found were .0016" (.04mm) per side from top to bottom when standing vertically. Is this the correct spec? Does this also count from side to side?

I also found the specs for housing width. It states that "if the width difference is more than .0023" (.06mm) the housing must be replaced". So is that to say I can be .0023" thicker, but 0.000" below my thickness? Since it only states "more" and dosnt mention anything about being under?

Reason being, I am going to attempt to machine a 13b Housing that has the typical wear marks on the outer edges of the chrome surface to 12a dimensions. Creating a mint 12a housing. If my tolerance is +/- .0016 then I can do this on my manual mill. But if it's tighter, then I it will need to be surface ground.

Anyone here done this on a manual bridgeport (or similar) style mill?

thickness is max subtracted from minimum. it is a thickness variation spec.

I'm a little confused by your reply...

But what I think your saying is I can be +/- .0023" on the total thickness?

I think what he is saying is you really don't measure the height, you measure the thickness. I maybe missing something but I never measured the actual height of the housings. I measure the thickness in the points described as per the shop manual.

I think I confused you now with my first statement about warpage. what I read states you must measure for warpage with the rotor housing standing vertically. not measuring the height of the rotor housing.

everything else was referring to the thickness of the rotor housing. I prepped a housing for this a few minutes ago, i just have to find time to machine it now. I thought the tolerances would be much tighter. I think it's very doable on a standard manual mill.

measure the thickness of the housing in 5-6 spots on the housing.

take your minimum measurement and that is your minimum thickness measurement, should be within spec.

then take the largest figure and subtract it from your lowest figure and that is your warpage, or thickness variation figure.

Sound to me you need to send them to a machinists that has done housing work before like Goopy perhaps.

Sounds to me like you are measuring housing 'warp', as in out of square, independent of housing width. If that's so, I can't find anything in the manuals that has you measure that, even in the competition manual; it only requires you to measure the rotor housing width in 4 different places to determine any variation in width.

"Measure the width, or thickness, of the housing at points A, B, C and D as shown in Figure 10. Points C and D are each 20 mm steps, individually beginning at point B. Compare the dimension at point A with the smallest of the other three, whichever it is. lf the difference is more than 0.06 mm, the housing must be replaced."

Anyway, if you are narrowing down 13b housings to make 12a housings, wouldn't it be best to mill them down to very close to the width required, and finish them off on a surface grinder to make sure they are true and within tolerance? Pretty hard to beat the flatness a surface grinder will give you, just go with the nominal width of a stock 12a housing for your finish, no?

Thats what I did earlier today. I was just making sure I was doing it correctly.

I am a machinist. I deal with much more complex parts on a daily basis. Milling down something is a basic machinist skill. Now this does have a large overall area to keep within tolerance. But with a quality fly cutter and a mill indicated in nicely, getting it flat and true shouldnt be to bad.


This is exactly how I did it earlier today.


Thanks for the help everyone.