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Davek0974
05-15-2009, 03:33 PM
Hi all,

i have a task coming up and i'm not sure of the best way to tackle it. Its a cylinder for a traction engine, the big lump on the floor here...
http://www.davekearley.co.uk/Engineering/LittleSamson/LS%20Pictures/sizecomp1.jpg

I need to bore out the cylinder to 3-1/8" and cut the saddle to a 6" radius. The only machine it will fit on realistically is my Bridgeport. The saddle length is about 10" and cylinder depth is about 7-1/2"

I have successfully cut a 6-1/2" radius on a shorter length saddle before and that worked well, it was done in two parts using the quill feed and a 3" boring head with 3/4" tooling.

This job is much larger though. The quill wont fit into the cylinder so i cant use the boring head on this. I had thought of turning the BP head 90deg and using a home made boring bar with some sort of sliding tailstock a bit like a horizontal borer, the tailstock idea was just to take some strain off the quill. This would mean i could use the table powerfeed and keep the quill locked in. I dont know if this would work or not or is there a better way? It would mean running the mill at 90deg for some time.

The other option is to make a longer boring bar and use the mill vertically, cutting from the knee lift, this sounds very tedious as i dont have a power knee lift.

Any ideas on a good setup?

Much appreciated
Dave

Carld
05-15-2009, 03:56 PM
I sure like your steam tractor, nice job.

Davek0974
05-15-2009, 03:59 PM
I sure like your steam tractor, nice job.

Thanks for that, i'm selling it now to provide funds for the big engine, i was hoping to keep it but you cant always do what you want i suppose.

Dave

x39
05-15-2009, 05:55 PM
If you have a lathe large enough, could you use it in the HBM role? Might be a bit tedious to set up, but would probably work well.

aboard_epsilon
05-15-2009, 06:07 PM
i could sell you an engine boring bar ..

needs motor and handle to be operational

35 and its yours

all the best.mark

deltaenterprizes
05-15-2009, 06:46 PM
Good job for a line boring rig

Davek0974
05-16-2009, 03:23 AM
Hi all,

thanks for the ideas so far, no it wont fit in the lathe as its, well i could do the cylinder in the lathe but not the saddle and both must be parallel and true to each other. I dont have a line boring rig. Thanks for the offer of the cylinder borer, is there a picture anywhere?

Dave

Timleech
05-16-2009, 04:00 AM
Can't you make up a long boring bar for your boring head, one with a cutting edge which comes just outside the head profile? You can make it thicker than your boring head fitting, just reduce the dia to fit in the head, that'll make it a bit stiffer. Even if the quill won't fit into the bore I presume the actual boring head will do so if you get the bar right, so the bar won't need to be the full length of the cylinder?

Tim

djc
05-16-2009, 07:52 AM
...I had thought of turning the BP head 90deg and using a home made boring bar with some sort of sliding tailstock a bit like a horizontal borer...

The other option is to make a longer boring bar and use the mill vertically, cutting from the knee lift, this sounds very tedious as i dont have a power knee lift.


Something a bit like this?

http://www.wrexham.gov.uk/images/museum/ironworks/cylinder_boring_machine_lg.jpg

Instead of a sliding tailstock, it might be easier to to have a fixed bar support (or even two, one either end of the cylinder and tight to it) and arrange for the bar to slide through it on a bearing. Hydraulic ram material is available in many diameters and might be good for the bar.

Could you rig up a cordless drill to provide a power knee?

In both cases, I'd be tempted to bore such that the bar is in tension when cutting (i.e. drop the knee/feed away from the head).

If you can do the cylinder in the lathe (either on a big faceplate or by clamping to the saddle and using a between centres bar), setting up to do the saddle shouldn't be too difficult. A parallel bar through the cylinder (again, hydraulic ram material), bushed if necessary, and supported on matched V-blocks would do, and you can indicate the bar in two planes to ensure it is aligned with the mill's axes.

John Stevenson
05-16-2009, 08:12 AM
What about an extension to fit your boring head?

http://www.mesatool.com/images/BHAttach2_large.JPG

http://www.mesatool.com/images/products/BoreAttach3.JPG

Far more rigid than a sticky out bar. Just make it deeper to suit your travel.

.

kvom
05-16-2009, 09:26 AM
Clearly you need a 3" boring head rather than a 4". Why not bore the first 5" (BP quill travel), then raise the knee 3" or so with the head inside to to get the last couple of inches. You may need to crank the knee a bit to make the adjusting screw visible.

Davek0974
05-16-2009, 11:22 AM
What about an extension to fit your boring head?

http://www.mesatool.com/images/BHAttach2_large.JPG

http://www.mesatool.com/images/products/BoreAttach3.JPG

Far more rigid than a sticky out bar. Just make it deeper to suit your travel.

.

That i think is the answer, a couple of longer shafts and a bar to take a tool should do it. I can use quill and knee for the cut and make a longer base bar for the big radius, should be better than a long tool.

Thanks for that

Dave

Davek0974
05-16-2009, 11:23 AM
Clearly you need a 3" boring head rather than a 4". Why not bore the first 5" (BP quill travel), then raise the knee 3" or so with the head inside to to get the last couple of inches. You may need to crank the knee a bit to make the adjusting screw visible.

Yes the head is a 3" one, as said above i'll make a version of that head adaptor with some 1" rod supports and try that with part quill and part knee, should do the job.

Dave

Rich Carlstedt
05-16-2009, 09:28 PM
Dave
just a heads up
When you tram the head in before doing the long bore work,
Put two angle plates on the table at right angles.
using a Dial indicator run the quill up/down and check for perpendicularity.
Then, without moving anything, raise the knee and see if you get movement.
If you do, lock the knee and see how much change you get. Hopefully it goes to zero.

We did long bores at work and when a knee wears, it can throw off the job.
You also may want to consider starting at the bottom ( !) and boring upwards ....
You gain two things.
No swarf buildup, as it stacks up in the area already cut , and second,
the knee is much smoother going down.( if it isn't worn to badly)
A bridgeport will cut in either direction.
Rich

x39
05-16-2009, 10:11 PM
What about an extension to fit your boring head?
....Far more rigid than a sticky out bar. Just make it deeper to suit your travel.
Again I learn something new on this forum. Great idea, thanks for posting.

J Tiers
05-16-2009, 10:46 PM
You said you can't do it on your lathe, what does the lathe swing? What you can't do on the faceplate might possibly bolt to the carriage.

With care, the axes of both saddle and cylinder might be placed at the height of the spindle axis, so that a boring bar between centers can do either one.

If your lathe won't swing 12", that is probably a non-starter, unless you make risers for HS and TS.

Davek0974
05-17-2009, 03:38 AM
You said you can't do it on your lathe, what does the lathe swing? What you can't do on the faceplate might possibly bolt to the carriage.

With care, the axes of both saddle and cylinder might be placed at the height of the spindle axis, so that a boring bar between centers can do either one.

If your lathe won't swing 12", that is probably a non-starter, unless you make risers for HS and TS.

Yeah, it can swing 12" (just) but not over the saddle or cross slide unfortunately. I haver seen the setup for doing both bores on the sadle but on a much smaller block.

I think the Bridgy is the only way forward and i will check the movements carefully first.

Thanks again

Dave

kvom
05-17-2009, 10:42 AM
This is more a question for Rich re boring upwards.

It appears from OP's description that the cylinder is a "blind hole". To move the boring bar outwards the boring head would need to be raised out of the hole to make the adjustment screw visible. But to move the cutter outwards he would need to move the boring bar off center and keep it there when he lowers the head into the bore. Then it would need to be off center to start the cut before moving it back off center. This means that the bottom of the bore would be slightly off center. Since it's the top of the cylinder that's probably not an issue, but I wanted to make sure I understood the technique.

Similarly, assuming OP knows the stroke, then the very bottom of the cylinder hole may not need precise boring, so that there is room for the swarf to fall into if he bores top down. In any case, it may make sense to bore top down until close to the final dimension, and then use the bottom up technique for the end.

Davek0974
05-17-2009, 02:27 PM
Update...


Made a pair of those boring head extensions, here's the short one in use...
http://d.yimg.com/kq/groups/17605961/sn/1920510160/name/DSCN0973.jpg

The other has a 6" arm so should be much better than sticking the tool way out.

Early results look extremely promising, the bore is +0.0015" from top to bottom using a mix of pwer quil feed and knee lift. I'm still roughing out at present so even if it holds that tolerance, it'll do nicely.

Running at 300rpm, powerfeed at 0.003"/rev and 0.015" DOC.

Thanks for the tip and pictures.

BTW, the bore is straight through, not closed.

Dave

knedvecki
05-17-2009, 02:58 PM
Dave,
For the large diameter, could you fabricate a live center mount that you could clamp to the dovetail column of your mill below the knee to catch the free end of a headstock / machine head mounted line boring bar. The work would be supported so that the diameter to be machined would be past the outside / back edge of the table with the machine head located on center of the large diameter and then just feed the knee and part up or down to make the cut. We used to have a collar bolted / clamped to our 2 inch diameter bar to hold the tool bit for large diameters.

John Stevenson
05-17-2009, 04:50 PM
Dave,
From the picture the bore looks to be a bit at both ends and relieved in the middle to take a liner ?

If so you could always bore and face one side then upside down it on a located plug bolted to the bed and do the other end.

If I have got this wrong and it's a straight bore then forget it and sod it I'll go and get another pint...........................

BTW that extended boring head idea wasn't mine, I spotted it on a web site and thought it would come in handy one day.

.

Davek0974
05-18-2009, 03:10 PM
Its sort of like you said with a ring at each end for the liner but there is a couple of other obstacles in there to machine as well so its practically a long bore job.

Its a wet liner and the steam passes around it on the way to the regulator at the top. The ends are sealed with loctite high temp, the covers locate the liner.

Dave