Porting Practice

[Paul Fithian]

Vielen Dank, Herr Doktor!

 

[Paul Fithian]

After additional practice, decided to port the cylinder that came with a new Holzfforma G660

Porting station setup that worked for me:


A rolled up towel section helps to support the cylinder at the different angles needed to get the bit in the right place.

I set up an air line and big trash can nearby to blow out the aluminum chips. Brush and dust pan helps keep the bench clean, better if the bench has no crevices and is a flat, smooth surface.

These are the tools I used for that cylinder, huge thanks to Randy for the Buckeye burr suggestion. The double cuts I tried before found a new home in the trash can


Here's how my first real porting job turned out:

 

[isaaccarlson]

Looks good! How are you liking the harbor freight grinder?

 

[Paul Fithian]

Looks good! How are you liking the harbor freight grinder?

Working OK for me and the little work I intend to use it for. I did remove the center spring and lubed it pretty well, it was basically dry.

For sure I'd buy a better one if I was going to do a lot of porting.

 

[drf256]

Paul, I’d bevel the ports more, especially that intake port.

FWIW, I have a Foredom with forward/reverse and have it hanging from the ceiling with double rope length. I have never snapped a shaft to date, because the rope acts like a shock absorber. If a burr gets caught, the motor will spin itself up as the rope coils and I can get off the pedal before the shaft snaps.

 

[GerbrandR]

Some nice tips in these threads. Didn't know that a single cutter would work better.

Not to highjack this thread, but I have a question about cutting squish on a lathe. A friend of mine has a lathe. I am quite sure that he only has 3 jaw chucks. I read that most people have a 4 jaw chuck for this. Is it really necessary to have a 4 jaw chuck to do mount the cylinder to the chuck?

 

[farminkarman]

Some nice tips in these threads. Didn't know that a single cutter would work better.

Not to highjack this thread, but I have a question about cutting squish on a lathe. A friend of mine has a lathe. I am quite sure that he only has 3 jaw chucks. I read that most people have a 4 jaw chuck for this. Is it really necessary to have a 4 jaw chuck to do mount the cylinder to the chuck?

While there may be some creative way to do it without a 4-jaw independent chuck, I would say a 4-jaw is required.

 

[Ketchup]

Some nice tips in these threads. Didn't know that a single cutter would work better.

Not to highjack this thread, but I have a question about cutting squish on a lathe. A friend of mine has a lathe. I am quite sure that he only has 3 jaw chucks. I read that most people have a 4 jaw chuck for this. Is it really necessary to have a 4 jaw chuck to do mount the cylinder to the chuck?

Potentially you could make a circular mounting plate with slotted bolt holes but it would be a lot more difficult to zero the bore.
Far easier to make a hand cutting mandrel with the 3-jaw. That method is slower and easier to make an irregular squish band but works just fine.

 

[isaaccarlson]

A few pieces of angle iron bolted to the faceplate with adjuster bolts in them are handy for centering the squish band. The base can be adjusted with the long bolts holding it to the plate. A beter setup (more repeatable and easy to adjust) makes it easier and faster. Once you have the setup for the faceplate, it only takes a few minutes to dial it all in and you can use it on any cylinder. Take light cuts. I bought a 10" 4 jaw last year and it still sits next to the lathe. They are handy for certain things, but not absolutely needed. A spider can do a lot as well, and can be mounted to a faceplate or directly to the spindle. Outboard spiders are nice for long skinny parts going through the head stock.

You'd be surprised what you can easily do without a 4 jaw chuck.

 

[Paul Fithian]

I can report that my practice sessions were crucial for development of technique and tools to raise the upper transfer ports on a 44mm cylinder I just completed.

These victims


revealed I needed a compact angle head grinder to reach some areas with a tool that minimized potential for adjacent cylinder wall damage. Two days after ordering, one of @srcarr52 ' s Lucky Dog Angled Rotary Porting Handpiece kits arrived with an extra burr, great tool. Thanks Shaun!


Made reaching the upper transfers and exhaust bevels simple and easy to control

 

[drf256]

Paul, did you inadvertently take some of the floor out of the uppers?

 

[Paul Fithian]

Only on a practice jug Doc! Top picture is a scorched one, bottom is the 44mm 026 cylinder you shaved.