I do nearly all tapping in a stand I made decades ago to the George Thomas design
Brian builds a Corliss
- Thread starter Brian Rupnow
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This is what I bought several years ago and use it all the time. I added some spacers under the head to give me more clearance.
https://www.zoro.com/hhip-mini-e-z-hand-tapper-3900-0252/i/G2515443/
https://www.zoro.com/hhip-mini-e-z-hand-tapper-3900-0252/i/G2515443/
Today I'm in design mode. Looking at making up a welding jig for the flywheel. I can mount my face-plate on the lathe, and make a center hole plug that is bored to be a precise fit into the faceplate center hole, with a precise center hole in the center plug which will accept the hub of the flywheel and center it. (I will leave the hub full diameter and about 3" long on that side only) I can use elements from my clamping kit for the mill to hold the outer rim of the flywheel firmly against the face of the faceplate and still allow access for my dial gauge to precisely center the outer rim before clamping it. The spokes are then slid thru holes in the flywheel rim and into blind pockets in the hub. In fact, at this time the spokes can be loctited into the blind holes in the hub. The spokes are sized so that when seated and Loctited into the blind holes in the hub, they are about 0.100" shy of the flywheel outer diameter. After 24 hours set up time, the faceplate gets unbolted form the lathe and taken out into my welding shop where the ends of the spokes are tig welded into the flywheel rim and any remaining depression in the hole gets filled with tig weld. Then the set up is dismantled and then the extra long hub which was previously held in the brown center plug gets mounted in the 3 jaw chuck and the o.d. of the flywheel gets turned very lightly to smooth the welded areas. Then with my reverse jaws in the lathe chuck, I hold the o.d. of the flywheel rim and finish turning and boring the hub center hole.
Having a quiet day today, cleaning up tiny bits that are outstanding. Today I ran into that age old conundrum "I designed it this way, but I can't make it on my machinery, so I'll redesign it to what my machines can make." Those small links with the series of holes in them were going to be totally different, but I had no really good way to cut the large radius required, so they ended up with parallel sides and some cosmetic holes in them. I have a serious bunch of rounding off to do, but all in all I'm happy with the way they are turning out.--And these are the smallest parts that I have to make. I heard back this morning from the people who are fixing my lathe, and it's not going to be cheap. It's going to cost around $700 to fix, but that's a lot cheaper than buying another lathe. Maybe tomorrow I will set up my rotary table and round off all the ends of the links in the picture.
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Hi Brian. Having built more than a few of Elmer Verburg’s engines I’ve tapped a lot of #2-56 holes. I haven’t broken a tap since I started using quality taps, cutting fluid and a guide.
My tapping guide is just mounted on the column of my small drill press and uses the same table.
I’ve been very happy with the Buttercut IPT cutting compound from Busy Bee.
By far the best small taps I have found are the Sowa spiral point taps from Thomas Skinner or United Tool Supply. They just cut like butter and it’s amazing to see a nice curly shaving coming off a 2-56 tap in steel.
And my goto in the shop is iEngineer on my old ipod
My tapping guide is just mounted on the column of my small drill press and uses the same table.
I’ve been very happy with the Buttercut IPT cutting compound from Busy Bee.
By far the best small taps I have found are the Sowa spiral point taps from Thomas Skinner or United Tool Supply. They just cut like butter and it’s amazing to see a nice curly shaving coming off a 2-56 tap in steel.
And my goto in the shop is iEngineer on my old ipod
Interesting that they call it a spiral point when every other maker would term that a spiral FLUTE tap. Or have you got it in the wrong box as their site seems to name them correctly? SOWA - Homepage
Spiral point tend to have straight flutes except for the end which is angled to push swarf ahead of the tap so meant for through holes.
The Spiral flute type act more like a drill bit with the helical flutes directing the swarf up out of the hole.
I tend to use Spiral flute most of the time now.
Spiral point tend to have straight flutes except for the end which is angled to push swarf ahead of the tap so meant for through holes.
The Spiral flute type act more like a drill bit with the helical flutes directing the swarf up out of the hole.
I tend to use Spiral flute most of the time now.
I just heard from BusyBee in Toronto, and my lathe is fixed and test ran for an hour. They missed the shipment to Barrie, but I will pick it up Monday in Toronto.---Brian
Question for anyone who may have built this engine. The 3D model I downloaded has the valve shafts in two separate pieces keyed together with a mechanical tongue and groove. Why is this so? Why not combine those two separate pieces and make them a one piece unit?
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Well, Brian, I have not built a Corliss valve engine, but that does not mean I don't have an answer! It allows the valve to be 'floating'. That is to say, not subject to any lateral forces from the actuating mechanism that would in time cause wear on both the valve and its chamber. Of course, it also means that those forces are taken by the much smaller driving stem and its bearing in the valve bonnet.
Charles, you may well be correct. I don't think that will be a real factor in a small model engine, but it is the only explanation I have received.---Brian
The only real work today was rounding over the ends of the links, which went very well. For all those that asked about how to make the built up flywheel, this is the way I will do it. Combine this drawing with the faceplate jig shown in post #84 and it will get you there.---Brian
raveney
Well-Known Member
Question for anyone who may have built this engine. The 3D model I downloaded has the valve shafts in two separate pieces keyed together with a mechanical tongue and groove. Why is this so? Why not combine those two separate pieces and make them a one piece unit?
Brian, I omitted the tongue and groove on mine, and made a one piece brass shaft. It seemed to work well.
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Just an odd idea from a know-nowt.... the valve is free-floating from the rotary actuator, as explained to minimise wear affecting sealing, but to permit the valve to float and seal, so the forces on the valve from steam pressure while the valve is closed do not or cannot react back to the valve linkage. I.E. The valve can float and seal properly, yet the only force reacting to the valve gear is torsional = friction for the valve in its hole.
I am learning loads from this one.
Thanks!
K2
I am learning loads from this one.
Thanks!
K2
My lathe is home!!! I decided I didn't want to wait until Monday to get it, so went down to Toronto and got it from the repair shop this morning. The lathe runs good and is back in place in my tiny machine shop. Now I have about a thousand bolts to put back in place and get set up to run again. I checked my mileage from here to North Toronto where Busy Bee has it's main Canadian warehouse. It is exactly fifty miles from my house to there. Not cheap. Cost was the $700 as quoted, and another $100 for provincial and federal tax. I have some more automation design coming in next week, and now I know what I'll do with the money.
Everything is back in place, all hooked up and ready to rock!!! My arse is well and truly whipped. Sometimes I really wish I was fourty again. I'm going to go upstairs, have a rum and cola and not do anymore today.
I was just finishing up the outer rim on my flywheel when my lathe quit last week. Tomorrow I have a couple more passes to make on the counterbore on one side, and then the outer rim is finished. Looking at it this evening, I see that the center hub will be easy--it can be machined and drilled using my lathe and then my rotary table on the mill to put the appropriate holes in it. The spokes are just 1/4" cold rolled steel cut to length. The issue I can see right now is how to position the outer rim to drill the 8 "spoke holes" in it. It is too large for my rotary table which has a 4" chuck mounted on it. Although the rim can be mounted on my lathe chuck, I have no way of indexing it properly, and I have no drill guide mounted to my lathe carriage to drill it while it is held in the chuck, although I could probably build something if I had to. Only thing I can do tomorrow while I have the rim mounted in my lathe chuck is to scribe a centerline around the perimeter. My best thought at the moment is to lay out the exact rim diameter on a piece of plywood, using a drafting compass. (This gives me an exact center). Then I can lay out 45 degree increments on the plywood, lay the outer rim on the plywood, and use a machinists square to transfer the 45 degree increment lines up onto the outer rim to intersect the scribed centerline. Drilling the holes won't be any problem--I can do that on my mill or drill press. Locating the holes accurately will be the trick.
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Calculate the circumference of the flywheel (pixD) Using cad draw a line that long and divide it into 8 (the number of spokes). Print it and cut a strip from the paper and wrap it around the flywheel. Center punch where the marks are on the paper. Drill.
If you need a longer strip than 11" (the length of a piece of paper) make two strips and tape / glue them together.
If you need a longer strip than 11" (the length of a piece of paper) make two strips and tape / glue them together.
Your lathe has a 40T gear on the spindle, make a simple detent or similar and index every 5 teeth. Scribe a line with an HSS tool in the tool post and then move the work to your drill press or mill to drill the holes.
Other options are to hold in the 4-jaw and use the jaws to index 4 holes at 90deg using the jaws as a ref, then set the jaws at 45deg and mark the other 4. Or cut a strip of paper, wrap around the rim and mark where it overlaps. Measure the length of the paper and then divide by eight and then wrap it back around the rim and use your eight divisions to mark the holes. fix a plywood disc to your rotary table and the rim to that so you can wind it around 45deg and mark the hole position. Hold your big chuck by the flange in the 4" chuck, it will be rigid enough for marking out on the rotary table, etc. So many other ways too.
Regarding the remaining turning on the rim, one reason they can let the smoke out is running too long at slow speeds which are often used on larger dia work. Run the lathe faster and take lighter cuts. It would also help to use a **GT insert as they are sharper and put less load and therefor the motor draws less current but previous suggestions to use these seem to have fallen on deaf ears. At the very least stop and let the motor cool as at low speeds the fan won't be doing much.
Other options are to hold in the 4-jaw and use the jaws to index 4 holes at 90deg using the jaws as a ref, then set the jaws at 45deg and mark the other 4. Or cut a strip of paper, wrap around the rim and mark where it overlaps. Measure the length of the paper and then divide by eight and then wrap it back around the rim and use your eight divisions to mark the holes. fix a plywood disc to your rotary table and the rim to that so you can wind it around 45deg and mark the hole position. Hold your big chuck by the flange in the 4" chuck, it will be rigid enough for marking out on the rotary table, etc. So many other ways too.
Regarding the remaining turning on the rim, one reason they can let the smoke out is running too long at slow speeds which are often used on larger dia work. Run the lathe faster and take lighter cuts. It would also help to use a **GT insert as they are sharper and put less load and therefor the motor draws less current but previous suggestions to use these seem to have fallen on deaf ears. At the very least stop and let the motor cool as at low speeds the fan won't be doing much.
I have used the tape around the chuck method with success to cut a 17 tooth gear, worked well!
I thought about using a Pi tape to do that. Haven't fully decided yet.
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