Granite surface plate, cheep!

[kyradawg]

Peace&Love , Darren

[snail]

Did i miss something at the start of this post? I thought the granite was to be a lapping plate ie put a gob of abrasive goo on it and lap the head flat(ish). Who would use their NASA quality surface plate for that? Not me mate! i'd use that domestic quality granite/ glass any day.
I think someone should pose a question in the "members only" area where we can have the mother of all discussions about frictionless bearings/aircraft tolerances/how perfect the Lister design is etc etc.
Seeing the posts about roller rockers and now surface plates, we obviously need to vent a little steam about who knows most about theoretical engineering and how it pertains to agricultural engines.
Will this be the last post in this thread?

Cheers,

Brian

[GuyFawkes]

Seeing the posts about roller rockers and now surface plates, we obviously need to vent a little steam about who knows most about theoretical engineering and how it pertains to agricultural engines.

Lister isn't an "agricultural" engine, but one of the highest quality engines you're ever likely to see.

[dkwflight]

Hi having a flat surface to promote sealing is common on all engines. If you want a good example most Deutz engines have "NO" head agskets.
Circular bearing journals are critical to long life too!
I thought that shot peening the journals and then building the surface up then machining them true would be wise. I have read comments to the effect the stock surfaces on some indian engines are not circular.
Gotta go to work now.
Have fun
Dennis

[Andre Blanchard]

A granite plate is not a lapping plate.  You will be cutting the granite as fast or faster then the cast iron head.
http://www.us-products.com/sitehtml/lapping.html

A lapping plate must be softer then the part being lapped.
Like so many other words that at one time were very well and narrowly defined "lapping" has been hijacked in common use and its meaning very diluted.
http://www.mini-lathe.com/Lapping/Lapping.htm
This is more properly called flat sanding.

For what you want to do, make the head as flat as you can with the tools you have.  I would get some abrasive belt 10 or 12 inches wide and clamp it to the granite counter top like show in the second link, 80 grit should work fine.  That way your flat plate will last longer.
http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=831&PMCTLG=00

[cujet]

A great use for such plates is to lap surfaces flat. Things such as intake and exhaust flanges. Aluminum cylinder heads and any other surface that needs to be made flat.

I use a granite slab with oil on top Then I lay a glass plate on top. The glass is then quite flat and makes a great working surface. One can use all sorts of lapping compounds. I even stick those circular DA sandpaper discs on the glass to sand something large flat. It works wonders on composites. Certainly the surface is not accurate to 1/4 wavelength of light. But so what? I got the warped caliper halves and brake pads to work quite well on the racing go kart using this method.

Chris

[bitsnpieces1]

Hi Group I've been thinking about a lapping plate, where to get one? 

He did say it was for a lapping plate NOT a surface plate.

[snail]

Lister isn't an "agricultural" engine, but one of the highest quality engines you're ever likely to see.

I knew someone would rise to it! . Why am I not surprised that it was the venerable Guy Fawkes!(Only kidding mate, we all love you dearly )
Of course,this is the great joy of the English language, we can both be correct, cs's being found mainly in agricultural situations.Before you start, i said mainly .( incidentally, never ask an aussie which team he roots for...)

I think we've found a good candidate for an all out brawl in the members only section.This could possibly outdo "Neighbours" (Sorry to the US majority, in- joke)

cheers,

Brian

[GuyFawkes]

This could possibly outdo "Neighbours" (Sorry to the US majority, in- joke)

My mate (south african) used to bonk kylies sister, we used to buy him beer because he would never let us book him an eye test.

[Stan]

Regardless of how you want to use it, you can get a granite surface plate that is 2" thick, by 9" X 12" from Lee Valley Tools accurate to +- 0.0001" (flattness I imagine) for $38.50 CDN plus shipping.  You don't have to pay hundreds of $$$$$!  www.leevalley.com
Stan

btw...I have thousands of dollars invested in the products of this company sitting in my basement workshop, so yes I do have a vested interest