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Old Yesterday, 03:06 PM
DJS Johnny
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United States, TX, Houston
Joined Aug 2007
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What Do They Do?

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Originally Posted by Reginald View Post
These are the only honing tools that I have used, rudimentary perhaps altough I recently saw a much larger version on those grapestones used in an engine rebuilding plant. If you want to use these the same method applies by moving up and down into the sleeve ! with oil of course
Reggie,

I have seen these types of tools. The Sunnen hone does one thing best. It makes a hole straight, round and untapered. For tapered sleeves I have found best results using a straight hone. As you work a lot of tapered sleeves the hone gets tapered and does not do as good a job. At that point I retrue the hone and go back to work. It seems counterintuitive, but that is my experience. I don't know if these tools are available in Europe, but can not imagine that there is not the equivalent tool there.

BTW, my wife is still looking for those diamonds you picked up for her in Antwerp!

Johnny
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Old Yesterday, 03:08 PM
Registered User
Reginald's Avatar
Belgium
Joined Aug 2004
4,402 Posts
So this is only for honing pistons ?
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Old Yesterday, 03:44 PM
DJS Johnny
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United States, TX, Houston
Joined Aug 2007
299 Posts
Anything!

Quote:
Originally Posted by Reginald View Post
So this is only for honing pistons ?
The hone will work on any hole. It will size crankshaft bushings or anything that is round. You just get the proper mandrel and stone for the diameter. The range for each diameter is fairly small. But most engines come in a limited range. Like most 2.5s are about 15mm plus or minus. I have never used mine on anything but model engine parts but it should work on anything. On the Tee Dee 049 homebuilt liners that had the ports cut as slots on the bore ID I got an "interrupted cut" shoe and stone. It worked extremely well without catching in the ports grooves. Being the cheap guy I am, I used it in the DJS sleeves and it worked great. When I bought other sizes later I also got this style of mandrel and stones because they cut the very smoothest. You could also use the honall to work on a hole in your car engine by using the hand drill drive.

The helical lap will also work on any external round thing. Just have the right size holder and sleeve for the part being worked. I actually put the insert in the lap holder and turn and hone it to the exact size for pistons. One insert for each size. You can also make your own inserts very easily. Again, I have never used it for anything except model engine parts.

They also make an internal helical lap, but I have never tried one. The Sunnen hone works too go for me.

Basically, they are very flexible and useful tools for dong work on round things.

Johnny
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Old Yesterday, 06:42 PM
DJS Johnny
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United States, TX, Houston
Joined Aug 2007
299 Posts
Sunnen External Hone

Quote:
Originally Posted by Reginald View Post
So this is only for honing pistons ?
I also have a Sunnen External hone, also. Looks a lot like a slingshot. It does a very nice job no matter how it looks. But, the Helical Lap works better and is easier to use. The Helical Lap works better than anything I know of for making pistons perfectly round. As it turns out, the Healical Lap is also the easiest to use. You can fit a piston to a sleeve so precisely it is hard to imagine using anything else once tried.

Pictures attached.

Johnny
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Old Yesterday, 09:15 PM
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Joined Sep 2011
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How big is your. Chrome tank John ? Mine is only one litre and I find I can get runaway with the heat if I'm plating a 40 size liner ,I also have to be very careful with 29s as well . The process tends to take over the heat a bit . It can get a bit expensive with buying internal and external hones when like me ,I might do 5/6 different size engines in a day ,it's great if you only do one size . I have an external Sunnin type that I made myself , but not happy with it so I grind all my pistons .
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Old Yesterday, 09:40 PM
DJS Johnny
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United States, TX, Houston
Joined Aug 2007
299 Posts
What Are You Doing Here!

Quote:
Originally Posted by Geoff Potter View Post
How big is your. Chrome tank John ? Mine is only one litre and I find I can get runaway with the heat if I'm plating a 40 size liner ,I also have to be very careful with 29s as well . The process tends to take over the heat a bit . It can get a bit expensive with buying internal and external hones when like me ,I might do 5/6 different size engines in a day ,it's great if you only do one size . I have an external Sunnin type that I made myself , but not happy with it so I grind all my pistons .
Geoff,

I thought you only sniffed ether! HA!

I use a one quart tank for the plating bath or the metric close enough. That is plenty of capacity for up to a 90. I find run away hearing is usually caused by something else. Oxide on center rod or "tired plating solution" are the most common. As you know, temperature is critical. 1 degree F (.5 C) or so is best. I find the temp always goes up at start up. I use a glass tube coil in the bath to control temperature rise with a large bucket reserve tank. When the bath goes up I start circulation and it controls it well. Very simple and cheap.

The Helical Lap is very reasonable. And I have not found anything that comes close for roundness. See my prior posts for other tools used. The Sunnen Honall and the stones are also reasonable. It does as good a job as the stand up machine. But, not as fast and easy to use. I can appreciate the effort involved with multiple different sizes in a day.

How are things you way? We are just getting back to a lot of flying here.

Johnny
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Old Yesterday, 11:49 PM
Diesel Danny
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Australia, VIC, Bellbridge
Joined Nov 2013
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Everybody seems to have their pet way to set-up pistons and liners.

One that I tried that worked out ok (although a mate said I was doing backwards) was to turn the inside of the piston, next turn the outside about 1 1/2 thou over size, drill for the gudgeon pin, then gently grind away the turning marks before lapping with a home-made adjustable lap held in a commercial die holder.

When the cylinder (base) just fits onto the cleaned piston part-off the piston, hold it on a jig (via the gudgeon pin) and finish the lapping by hand. Testing the fit as you go by ultrasonic cleaning and using a trace of tallow.

For Cox cylinders with internal transfer ports a simple expanding lap seems to work.

* Danny M *
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Old Today, 06:15 AM
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Joined Sep 2011
205 Posts
G'day John , I do lookin here every now and then . I'm fine , trying to get Grant qualified for the F2c team for the W/Champs next year so a bit busy , plus a fair bit of building in the last month for the SAM champs at Easter. Reason I asked about your tank is I'm working on putting a glass cooling coil in mine and was wondering. If I should pump it through or total loss ,and if so , how to control it ,auto or manual ?
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Old Today, 10:15 AM
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Belgium
Joined Aug 2004
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That adjustable or expanding lap of yours is what my late friend Harry used for honing the cylinders of the Anzani he built, only difference is that his was made of red copper. I have included picture of the disassembled engine when he was finishing it. No castings were used. Engine belongs to his grandson who now does run High Performance Garage.
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Old Today, 12:16 PM
DJS Johnny
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United States, TX, Houston
Joined Aug 2007
299 Posts
Great Work!

Quote:
Originally Posted by danny mz View Post
Everybody seems to have their pet way to set-up pistons and liners.

One that I tried that worked out ok (although a mate said I was doing backwards) was to turn the inside of the piston, next turn the outside about 1 1/2 thou over size, drill for the gudgeon pin, then gently grind away the turning marks before lapping with a home-made adjustable lap held in a commercial die holder.

When the cylinder (base) just fits onto the cleaned piston part-off the piston, hold it on a jig (via the gudgeon pin) and finish the lapping by hand. Testing the fit as you go by ultrasonic cleaning and using a trace of tallow.

For Cox cylinders with internal transfer ports a simple expanding lap seems to work.

* Danny M *
Danny,

Beautiful custom made tools and fixtures.

I make homemade pistons exactly as you do. If your mate thinks it is backwards. I am also backwards too I guess. Or, In my case I might be "upside down" relative to you? Anyway, I also turn the inside complete (outside diameter slightly over) and punch the wrist pin hole plus cut it off. Then I made a simple tool from a short piece of stock (picture) and the upper end of a rod. The rod end is drilled and tapped, the tool is drilled and tapped. Then a wrist pin is put in the piston/rod end and a short all thread used to hold the piston against the end of the tool. This way you can finish the outside and top of the piston. Since the top is exposed, you can put a flat, cone, rounded or whatever shape you want on it. I make the tool where it seats on the inside wrist pin boss shoulder. That way, if you notch the skirt it still goes on straight. Then I take it out of the lathe and use the lap. I hold the lap in one hand and use the protruding piston tool as a handle. For the fitting you can drop the whole piston/tool in the uson to clean, check the fit and do more work if needed.

Hope this info is useful. I find every time I see someone else's methods I learn something that makes working on these things better and/or easier.

That is a really beautiful little cox based side port engine!

Johnny
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Old Today, 05:45 PM
DJS Johnny
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United States, TX, Houston
Joined Aug 2007
299 Posts
Insert Material

Quote:
Originally Posted by danny mz View Post
Everybody seems to have their pet way to set-up pistons and liners.

One that I tried that worked out ok (although a mate said I was doing backwards) was to turn the inside of the piston, next turn the outside about 1 1/2 thou over size, drill for the gudgeon pin, then gently grind away the turning marks before lapping with a home-made adjustable lap held in a commercial die holder.

When the cylinder (base) just fits onto the cleaned piston part-off the piston, hold it on a jig (via the gudgeon pin) and finish the lapping by hand. Testing the fit as you go by ultrasonic cleaning and using a trace of tallow.

For Cox cylinders with internal transfer ports a simple expanding lap seems to work.

* Danny M *
Danny,

Over the years I have found the cast iron inserts work best in the piston lap for all piston materials. They seem to keep their diameter and roundness better than the brass ones they sell.

Johnny
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Old Today, 05:49 PM
Diesel Danny
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Australia, VIC, Bellbridge
Joined Nov 2013
407 Posts
Thank's guy's. A little encouragement goes a long way.

The piston holder that I use is like the one at http://modelenginenews.org/index.html (look for the July 2007 Tech Tip).

One other handy tool that I made was an adaptor to hold my Dremel in the toolpost. It's handy for grinding iron pistons and hardened liners (though not a precision tool)

I held it in a bored block as not comfortable with the overhang of the 'nose-mounted' versions. Am currently thinking of making a new nosepiece to allow the use of ball bearings instead of a bush. This should improve the accuracy.

* Danny M *
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Old Today, 07:39 PM
"Unnecessary Necessity"
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Canada
Joined Sep 2006
6,257 Posts
At the bottom of the page:
http://modelenginenews.org/ed.2007.07.html#tt
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