ACF cylinders

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flat38
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Re: ACF cylinders

#16

Post by flat38 »

I must eat a bit of crow here. I reported that my cylinder bores were egg shaped by .020". I was using a new bore gauge and when I remeasured yesterday I realized that I read .002" as .020". The gauge is marked 10, 20, 30 etc. and I misread it. I will not need to re-bore, but I do need to cut the base flange to be square to the bore and remove about .050" from the deck to get proper squish. I have made a tapered mandrel for the cylinder bore and will turn it between centers.



Buddhahoodvatoloco
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Re: ACF cylinders

#17

Post by Buddhahoodvatoloco »

It's not Crow hombre, it's a admirable manning up. Kudos :lol:
flat38 wrote:
Tue Nov 26, 2019 2:48 am
I must eat a bit of crow here. I reported that my cylinder bores were egg shaped by .020". I was using a new bore gauge and when I remeasured yesterday I realized that I read .002" as .020". The gauge is marked 10, 20, 30 etc. and I misread it. I will not need to re-bore, but I do need to cut the base flange to be square to the bore and remove about .050" from the deck to get proper squish. I have made a tapered mandrel for the cylinder bore and will turn it between centers.

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Re: ACF cylinders

#18

Post by Raytag »

flat38 wrote:
Tue Nov 26, 2019 2:48 am
I must eat a bit of crow here. I reported that my cylinder bores were egg shaped by .020". I was using a new bore gauge and when I remeasured yesterday I realized that I read .002" as .020". The gauge is marked 10, 20, 30 etc. and I misread it. I will not need to re-bore, but I do need to cut the base flange to be square to the bore and remove about .050" from the deck to get proper squish. I have made a tapered mandrel for the cylinder bore and will turn it between centers.
I`ve zero knowledge about flatties
We`re talking castiron barrels aren`t we ? .002 ovaled ? Do you intend to straighten the bore with a hone?
Would love to see that mandrel.

Ray

flat38
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Re: ACF cylinders

#19

Post by flat38 »

Yes, they are cast iron. The out of round is only at the bottom of the bore and the small part is the same as the rest of the cylinder. I will most likely touch it up with a fine stone as the clearance is less than I would like. It is .003" and I would like .0035 to .004". There are also some deep hacks from pulling the roughing hone out too fast at the top of the bore. They need to be smoothed out a bit. I will try to post a pic of the cylinder on the mandrel when I have it in the lathe.

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Re: ACF cylinders

#20

Post by Larry »

Does the cylinder become round when the base is torqued?

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Re: ACF cylinders

#21

Post by RooDog »

Larry wrote:
Thu Nov 28, 2019 2:58 pm
Does the cylinder become round when the base is torqued?
Very good question. Perhaps all this work , except squaring the base to the bore, should be done with both base and head torque plates, another added expense....
....RooDog....

flat38
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Re: ACF cylinders

#22

Post by flat38 »

I have both base and head torque plates and they will be used when I hone the cylinders. Whether or not torquing the base will make the bore round is not a concern at this point as the bases need to be trued to the bore. The smallest part of the out of round condition is the correct bore size and is only at the bottom below the base flange. it does not concern me as this will only see the skirt of the piston anyway.

flat38
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Re: ACF cylinders

#23

Post by flat38 »

I got the cylinders trued and faced off for the proper piston squish. The picture shows the cylinder on the mandrel in the lathe. The iron is pretty good quality, fine grain and machines well. If anyone has these cylinders, I would recommend removing the intake nipples as they were installed without sealant of any kind on the threads.
Image

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Re: ACF cylinders

#24

Post by Buddhahoodvatoloco »

Mad skills. :wink: :wink:
flat38 wrote:
Sun Jan 26, 2020 2:30 am
I got the cylinders trued and faced off for the proper piston squish. The picture shows the cylinder on the mandrel in the lathe. The iron is pretty good quality, fine grain and machines well. If anyone has these cylinders, I would recommend removing the intake nipples as they were installed without sealant of any kind on the threads.
Image

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Re: ACF cylinders

#25

Post by Raytag »

Thanks for showing your setup! Nice , that way you can work on both ends and and prevent the carriage to slide over the maybe worn bedways.
Is this mandrel adjustable ? Or are you using a new mandrel for every needed oversize?

My tools are a pita to setup. I can dial it in no worries but very timeconsuming. Not too happy with it. Bloody heavy :cry:

Reg torqueplates: My limited experience is that maybe the 4th definitly the 5th oversize you can meassure the oval shape in the lower half of the barrel. I use them for honing too.
Attachments
boring_cylinder.jpg
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Re: ACF cylinders

#26

Post by Frankenstein »

Raytag,
Now that's a Teutonic Torque Plate! :D Meaning absolutely no disrespect and total admiration. I'm in awe of your setup.
I spent a year and a half in your country back in the late '60's in the Army and developed a great deal of respect for your country and it's people. (Aschaffenburg)
Anyway, nice setup
DD

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Re: ACF cylinders

#27

Post by Raytag »

:lol:
Hold it

For the lack of an independent 4-jaw chuck I needed to fabricate that Teutonic Torque Plate.
The Teutonic Torque Plate will be mounted on the faceplate of the lathe
You can see that 4 steelblocks with a bolt protruding. With these bolts I zero in the cylinder. These bolts will push the Teutonic Torque Plate :mrgreen: in the direction I need to. The cylinder is tightened with the proper torque on that Teutonic Torque Plate :mrgreen: :mrgreen:

Too heavy too cumbersome .... but it is exact, way more precise than the proshops I know cause they don`t give a damn wether the base is true to the bore

Ray
Attachments
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flat38
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Re: ACF cylinders

#28

Post by flat38 »

Raytag,
Very nice setup.

My original intent was not to have the cylinder end up on the end of the mandrel. I made it in my shop at 68 degrees F and the cylinder fit at about the center of the mandrel. My lathe is not big enough to swing the BTFH cylinder so I was using a borrowed lathe in a non heated shop at about 45 degrees F. The difference in contraction of the steel mandrel and the cast iron cylinder caused it to fit at the small end. The mandrel is not adjustable. I made it for these cylinders. I do not plan on doing this again. I have bored flathead cylinders bolted to the base flange and found that they tend to move around a bit due to the offset weight of the valve side of the casting and the distance of the head surface from the base flange. I have a torque plate that bolts to the head surface and is used in a 4 jaw chuck. It has a counterweight to limit vibration.

I did not machine both ends in the same setup. The big end of the cylinder would not clear the carriage. I had to true the base flange and then turn the cylinder around on the mandrel to true the head surface to the bore. I then had to mock the cylinders up on the lower end to measure piston height. After that I put the cylinders back on the mandrel to cut to length for proper deck height.

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Re: ACF cylinders

#29

Post by Raytag »

I asked about wether it is adjustable cause I`ve seen a pic once.
It basically looked like an adjustable reamer.
At both ends a huge fine thread with fabricated nuts.
The mandrel maybe 3" in diameter with 4 slots every 90 degrees.
In each slot is 1 blunt blade.
The slots were milled, guessing here, with a slope of maybe 5 degrees.
When fitting the mandrel through the cylinder, he tightened one nut, therefore all 4 blades climbing, enlarging the diameter of the mandrel, till the barrel
was tightened with those 4 blades. Then tightening securing the blades with the second nut on the other end of the mandrel
When facing both ends you take very light cuts anyway so the pressure of those blades was enough.

His aim is it to avoid boring the cylinder (if permissable) and to hone only from one size to the very next oversize and to be
100% positive that the bore is true with the base & head surface and when honing only, saving precious meat of the barrel.
I really like that type of fixture. His shop is somewhere in the NE-States cannot remember

My setup is simply too heavy. The 20" faceplate of the lathe is a 100lbs already and I have to lean over the lathe ... my back is crunching everytime oh man

Still cracking up about Frankensteins` comment. Thanks for that man ! :lol:

ray

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Re: ACF cylinders

#30

Post by Frankenstein »

Glad to oblige, :D

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