Cylinder boring

[cdyoung1985]

Your biggest enemy with boring the cylinder will be the boring bar flexing on you. Coolant isn t so critical. More of a luxury for this application. Use the biggest diameter bar you can and the least amount of stickout possible to do the job. I would stay away from carbide and use high speed with a very sharp edge. Carbide needs to get under the matarial and may cause you more grief with it wanting to rub and flex with the little amount of material you want to remove. Yes the hone is needed to give you the cross hatch pattern to help seat the rings.

Thanks, very good information. Figure I'll try the dirt bike first since it isn't such a big deal. Going to be a while, but not that long it that makes sense...

Before experimenting with creating scrap check into having it done.

Places that do this have correct everything to get it done correct and to spec.

Cost of tooling likely more than that of the job.

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It would be cheaper than doing one, yes. But I don't just want 1 cylinder bored in my life. We have most of what we need, and I have the capability to learn it. Probably changing my degree from a welding certificate to an associate's degree because it includes courses for machining. I'm a built not bought kinda guy. Wouldn't be surprised if we build the tool to bore my cylinder. Not planning on it, by it isn't beyond the realm of possibilities.

 

[MarkM]

I like your approach. How will we be craftsman if we take the easy way out. A challenge today is a skill for life. No biggie making your boring bar. Rigity rigity Rigity. Figure how your going to hold the cylinder and think about clearance on the end close to your chuck. You may need to shim it againt the chuck to allow the tool to finish the bore. Not needed but if your looking for a challenge and a great boring bar do it with an eccentric rather than concentric to aid with rigity. Drill a deep hole from the back end and tap it for a bolt. Fill it with lead or soder and tighten the bolt to add pressure on the lead once cured. Great dampening effect and does wonders for vibration.

 

[BogusSVO]

General rule of thumb is bore the bore .003 smaller than the finish bore you want
Your hone that last ~.003 or so out to set the PTW

Most all blocks are bored dry and honed with oil

Bad thing most all parts store hones are just glaze brakers

Look at sunnen AN hone stones,

BTW my avatar is a Kwik-Way FN boring bar

 

[cdyoung1985]

I like your approach. How will we be craftsman if we take the easy way out. A challenge today is a skill for life. No biggie making your boring bar. Rigity rigity Rigity. Figure how your going to hold the cylinder and think about clearance on the end close to your chuck. You may need to shim it againt the chuck to allow the tool to finish the bore. Not needed but if your looking for a challenge and a great boring bar do it with an eccentric rather than concentric to aid with rigity. Drill a deep hole from the back end and tap it for a bolt. Fill it with lead or soder and tighten the bolt to add pressure on the lead once cured. Great dampening effect and does wonders for vibration.

I like that, a challenge today is a skill for life.
And you meant rigidity, not rigity right? Want to make it as unbendable as possible?
Thinking I could make a gusset that runs most of the way down the bar? Would think as long as it doesn't contact the cylinder it wouldn't be an issue.
Unsure of what eccentric and concentric are at this point. I'm far from a machinist, but I have a thing for pretending I know what I'm doing, and before long convincing others I really do. I don't, but don't tell them that.

 

[Silverbullet]

You really do need the ring set to Ck your bore. You'll need your oversize set to get them fitted . Bore to your ten over and take the compression ring and place it in the cylinder and Ck the ring gap it must have room. If the ring fits to loose or tight your engine won't perform or last. Your specs, will tell you what's needed. Small engines have been my extra income for. Years

 

[Silverbullet]

Thanks, very good information. Figure I'll try the dirt bike first since it isn't such a big deal. Going to be a while, but not that long it that makes sense...

It would be cheaper than doing one, yes. But I don't just want 1 cylinder bored in my life. We have most of what we need, and I have the capability to learn it. Probably changing my degree from a welding certificate to an associate's degree because it includes courses for machining. I'm a built not bought kinda guy. Wouldn't be surprised if we build the tool to bore my cylinder. Not planning on it, by it isn't beyond the realm of possibilities.

Very easy to make a boring bar.

 

[MarkM]

Yes I meant rigidity. Guess I need to go back to school. As far as the eccentric. Say a shaft would need to be turned down between centres. A concentric shaft has the centre holes drilled in the centre and then turned down. An eccentric would have the centre holes offset and then turned down between centres. The portion being clamped and holding your tool would be the concentric portion and in between would be your eccentric portion. Really not needed. It adds a bit RIGIDITY and some clearance.
I also meant a challenge can lead to knowledge that will stay with you for life and yes the possibility of a scrapped part may enter the equation but how are we going to learn?
I should do a better job of proof reading before I hit the post button. Way too much on my plate at the moment.

 

[TomS]

For what it's worth many years ago, I'm talking about the 70's, I bored the cylinder on my 125cc Honda two stroke. I made a mounting plate that replicated the cylinder mounting flange on the case. Set up the mounting plate in the lathe, dialed in the mounting plate bore, then faced the mounting plate. Bolted the cylinder to the plate and bored the cylinder to size leaving a few thou for honing. I had a local auto machine shop do the honing. Motor ran great.

 

[MarkM]

Hey BogusSVO I wonder if the Kwik-way fn Boring bar could be configured to do mobile line boring. In the ball park of a decent mag drill as far as price goes. On it s own without the stand could you replace the spindle shaft with a long shaft to be set up using cones for alignment between bores say for example a backhoe bucket? Off on a tangent here but have never worked in an automotive machine shop and it intrigues me.

 

[benmychree]

A cylinder boring bar is made to work vertically or at worst at 45 or 60 deg. they are not made to operate horizontally, the issue is internal lubrication.