cut the base on my 385xp on the bridgeport mill!

[Mattyo]

UPDATE: see page 9 for vid



Squish measured at .036 ..... so I cut .016 off the chassis....

good idea? bad idea? Either way, I can run a gasket now at .020 squish.....hopefully. haven't put the P&C on it yet!

I took video of the process, so when I get the saw together and it edited, i'll post it

-Matt

 

[Red97]

Should be fine, just check the squish and don't bottom the bolts out in the case.

Nice job.

 

[Mattyo]

gotta check the skirt too.... thanks for the advice

 

[old-cat]

Now you just need to figure how to make the squish band square with the cylinder. Most cylinders are off.

 

[Mattyo]

sounds to me like that type of stuff is a bit out of my league... how to get anything square? its an issue... who knows if the mill table is really perpendicular to the mill head? i'm sure its close, but I've never calibrated it...

in this case, I would have had to check squish on all 4 sides of the piston, then accounted for that when I leveled the plane of the chassis... to within .001" .... if you watch the video, i kinda got lucky. for 99.99% intents and purposes....what I'm doing here has got to be so far above and beyond what most people do with saws... gotta be close enough

 

[Mattyo]

actually, thinking about it... it might be possible to clamp the cylinder head in the mill ... make sure its vertical.... and cut the base with the mill, perpendicular to the piston plane. that'd be an interesting exercise ...

 

[Jim Timber]

Get a boring/facing head and you can cut the squish band on the mill.

I got a nice one for $200 about 6 years ago on ebay.

 

[weimedog]

Squish measured at .036 ..... so I cut .016 off the chassis....

good idea? bad idea? Either way, I can run a gasket now at .020 squish.....hopefully. haven't put the P&C on it yet!

I took video of the process, so when I get the saw together and it edited, i'll post it

-Matt

View attachment 389694

Why not? Careful about how far the cylinder flange goes into the cases... but other than that.... why not if you have the skills and tooling. For many.... its less of a financial risk to cut a cylinder, or simply remove the base gasket if there is enough squish.

 

[fearofpavement]

The squish band being square to the piston has nothing to do with the flange on the case. It has to do with the relationship between the cylinder's top and the piston's top. The piston is going to center itself in the cylinder so any machining to square the squish band would reference the cylinder walls, not the base flange.

 

[jar944]

actually, thinking about it... it might be possible to clamp the cylinder head in the mill ... make sure its vertical.... and cut the base with the mill, perpendicular to the piston plane. that'd be an interesting exercise ...

A lot easier to do it on a lathe.

 

[old-cat]

That's exactly what I was hoping he would finally realize!

 

[Wagnerwerks]

Hey.... You work with what you got. When I was 14 I stick welded all my floor pans into my bug.

They never fell out, but they weren't pretty.

 

[Mattyo]

I have a lathe. In fact, it might even be possible to put the cylinder on the lathe. I wanted to see if this was possible. I know you guys think its easier on a lathe, but I'm not so sure. I've seen it done, and ideally you need a long rod ...same diameter as the piston and then a live center up against the head. Off hand, I don't have any material big enough to make a mandrel like that. a block of wood maybe?

so I figured I'd try this. took about and hour and a half to get it level with shims in a vice that was BARELY big enough to grab it...

it also seemed to me that it was less risky to mess up a case than an oem cylinder .... I can just find another case.... new oem jug... I dunno.

so thats what I was thinkin, wagnerwerks is right, I worked with what I had. actually, I think this is quite pretty... though one day I'll get a cylinder on the lathe and play w/ that.

 

[AKDoug]

Masterminds cylinder inserts are made of plastic.

 

[Mattyo]

wish I had some plastic that was that diameter... wonder if I can order some from ebay.....

 

[Mattyo]

yup

http://www.ebay.com/itm/UHMW-Plasti...076?pt=LH_DefaultDomain_0&hash=item1e96757584

 

[Andyshine77]

There is nothing wrong with machining the case. In fact reducing case volume a little can be a good thing. Some of the best builders prefer this method. It's nothing new.

 

[Freakingstang]

i've cut cylinder bases on a mill and one crankcase. I don't have a lathe so I did what worked. it might be a little tricky getting the cylinder square to the head and the table, but once you do, its not a big deal at all. Just a couple years ago, everyone cut the bases and not the squish, well almost everyone.

 

[Sierradmax]

rotary table?

 

[Mattyo]

Would be nice to have a rotory table...