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Tharper

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Tharper last won the day on May 16

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  1. Tharper

    WW1 Thornycroft restoration

    Nice work! Another trick you can do with the paper gasket is give it a quick coat of shellac just before you do the assembly when its still wet - this makes a nice seal and makes the gasket more durable. When I disassembled my big Wisconsin T-head many of the gaskets were original and done this way including under the blocks , the oil pan and the timing gear cover.
  2. Tharper

    WW1 Thornycroft restoration

    A while back my students reverse engineered a magneto coupling used on early Wisconsin engines. Here is a rendering of the assembly. The disk is leather. The splined hub is keyed to the input shaft the eared coupling is keyed onto the magneto. I am not sure if this would help but its an alternative. We have a set of shop drawings and a set of patterns as well. Best regards, Terry
  3. Tharper

    WW1 Thornycroft restoration

    Or.... press start on the CNC mill :-D
  4. Tharper

    WW1 Thornycroft restoration

    In regards to your core boxes.... been there done that! I found the simplest way was to make male masters than use those to cast the actual core box in plaster-of-paris. Love seeing the progress and I cant wait to here that engine roar into life! Best regards, Terry
  5. Tharper

    FWD arrives

    Today we finished milling out the core boxes for the valve covers for Bob's FWD. Again we used the Tormach 440 (Love this machine!) Now we just need to mount the patterns on a backer board, seal and finish them. The core boxes will be joined together and mounted in a frame and will be sealed and finished as well - then its off to the foundry!
  6. Tharper

    FWD arrives

    We started work on the patterns and core boxes for the valve covers for the Wisconsin in Bob's FWD. Interestingly the original piece we are using as a "go-by" arrived here in far northern Maine from great Britain via Connecticut. I suspect at least one of you might have been involved with that transaction. Having the actual part on hand has saved us quite a bit of work and... with it sitting on my desk at school (soon to be shipped back from where it came) no small amount of wonder among the students. "A 1917 FWD?? What's that?" Anyway, we (my students and I) started by developing a 3D model using Autodesk Inventor Professional. (I teach Drafting & Engineering Technology to High School students). Once the model was completed we generated a set of 2D working drawings. Usually I would disappear into my shop and turn this piece out using my old 1943 Southbend lathe. However.... this time I decided to use the Tormach PCNC 440 CNC mill we have newly installed in our classroom lab space. Using Fusion 360 we generated the setups and the tool paths then post processed it to PathPilot. I cannot say it is faster than using the old Southbend but it sure is nice. Here is a photo of the patterns ready to be mounted on the backerboard. The core boxes should be cut this week. Best regards, Terry
  7. Tharper

    WW1 Thornycroft restoration

    Not to beat it to death but I thought I would provide some more info on DIY etched plates. I use a product called PNP Blue http://www.techniks.com/ Its used to etch circuit boards. I create my artwork using AutoCAD but any graphics program will work. The artwork is transferred to the PNP Blue using a laser printer. (remembering that it has to be mirrored) and make sure you print on the proper side. I usually make artwork for both the front and back with registration marks. Once folded the brass sheet can be inserted and the ends stapled to from a little envelope. By masking both sides of the plate it allows the etchant to work all the way through around the perimeter and create any holes etc. If you don't do this than you will have to protect the back of the plate. (I good layer of packing tape works well) than cut to final shape by hand and drill any holes etc. The brass sheet is prepped by making sure there are no burrs etc. around the edge and going over it with very fine steel wool followed by a washing in lacquer thinner You have to be very careful not to get any finger prints etc. on the brass. The next step is to transfer the image on the PNP Blue to the brass sheet. Heat is important. I usually heat the brass in the oven. Once the PNP Blue is in position I go over it with a hot clothes Iron (no steam) to transfer the image. A quick dunking in ice water and you can peel the backing off. Front of plate ready to etch: Back of same plate: Any blemishes or scratches in the masking coating can be touched-up with a permanent marker. Then its to the acid bath. I use Muriatic Acid cut with hydrogen peroxide. The trick is to get enough ratio of acid to Hydrogen Peroxide that will allow the acid to work quickly but not lift the mask. I good trick to help prevent this is to apply permanent marker to the cut edges of the plate. During the etching process I make sure to agitate the solution so the areas being etched are always exposed to fresh etchant. And... here it is right out of the etchant and after a quick rinse in cold water. Note the registration makes that allowed me to align the front and back masks so all the holes and the perimeter would be cut through. A washing in Lacquer Thinner will remove the mask. Painting: Yes you can use chemical blackeners - unless the original was done that way I do not. Typically after a clean-up and polish with fine steel wool I spray on the background fill. I like to use off the shelf rattle can enamels. To ensure the paint is fully cured I bake the plate for a bit. Once I am sure that the paint is fully cured wrapping a piece of 800 grit wet/dry paper around a hardwood block I set to work removing the paint from the high spots. Its important to work slowly - let the sand paper do the work not muscle! Sand across the whole plate not just one portion. Also make sure you are working on a hard flat surface. (I have a piece of polished granite countertop I use) I frequently rinse the sand paper in soapy water - this helps prevent galling. Do not over sand! Its fairly easy to remove all the relief. Once the background is in than you can add any other colors - sometimes I end up using a toothpick to carefully "drop" the paint into place. Sand again than polish with very, very fine steel wool and your done. Here is a motometer face I made for a collector. The face has been silvered. I hope this helps! Best regards, Terry
  8. Tharper

    WW1 Thornycroft restoration

    Remember this was a day and age when air cleaners were rare indeed and engines were not far removed from the "total loss" oiling systems. Some T-head manufactures did provide protection for the valve gear - Sterling hid their valve stems and guides behind covers in the blocks. Wisconsin used cylindrical aluminum shrouds on some of their engines that enclosed the stems and springs. Rather than keep out dust their purpose was to contain the "oil mist" blowing up through the lifters to lubricate the valves. Once again... magnificent work.
  9. Tharper

    WW1 Thornycroft restoration

    I ran into a similar type in a 1909 Jackson. The mains were simply machined Babbitt inserts with no backer. They were indexed in the crankcase and caps with steel dowels. Here you can see the aluminum caps and the two Babbitt "inserts". I am assuming they did it this way because of the difficulty of bonding poured Babbitt to aluminum.
  10. Tharper

    WW1 Thornycroft restoration

    You are correct - However, many times you will find these old T-heads with bent rods. As you have probably discovered its very easy to have things jamb-up and the rods take the weight of the block if the pistons get a bit off kilter. A while back I was helping my brother pick-up his airplane after its annual - while chatting with his mechanic he mentioned how with the old engine when valves would stick he would take-out a spark plug, insert a length of nylon rope into the bore. When he cranked the engine over by hand the piston compressed the rope and pushed the offending valve closed. The rope could be easily removed since one end was left hanging out the spark plug hole. Needless to say... one could use a length of rope coiled-up in the combustion chamber to keep the pistons from sliding too far up and popping a ring over the top of the bore. Once the block is suspended upright over the crankcase with straps holding the piston in you could pull the rope out and lower the whole assembly in place. Just a thought.... On another note... its great to see the engine going together - I cannot wait to here it run. You mentioned scrapping in the bearings - are they cast-in-place Babbitt or are the bronze backed Babbitt shells? Best regards, Terry
  11. Tharper

    WW1 Thornycroft restoration

    Its great to see this engine come together! In regards to a gasket between the blocks and crankcase - On my T-head Wisconsin they used thin paper gaskets. They were nothing more than shellac coasted brown paper. The gasket and the block were assembled while the shellac was wet. In fact all the gaskets were done this way. Best regards, Terry
  12. Tharper

    WW1 Thornycroft restoration

    Hello John, Its just a core sand (as close to 100% silca as possible) There a hundreds of recipies for core binders - Flour & Molasses is one that works well, Linseed oil use to be used a lot. Now sodium silicate is quite popular. This is cured by exposure to CO2. You can even make no-bake cores from green sand. Baking time and temp depends on the size of the core. Bigger cores need to be baked at a lower temprature for a longer period to insure they are cured all the way through. I have not heard of using soft versus hard cores...but the pattern must take into account the shrinkage rate for the metal and alloy being used. What the foundry guy does with gating, risers, shrink bobs etc. also affects this. Steve, I live in the Pine Tree state. The pines here were once emblazoned with the King's broad arrow mark and were favored for masts for the Royal Navy! Best regards, Terry
  13. Tharper

    WW1 Thornycroft restoration

    Hello David, That would be a very short thread! Anyway...the core is actually sitting in a rectangular core print. Its formed by a corrosponding piece which is pinned to the back of the pattern. Its removed so the pattern will lay flat during ramming of the bottom half of the mold. Once its been flipped over the piece that forms the core print is attached (aligns with dowels) and the other half of the mold is rammed leaving the imprint for the core. It worked quite well. Best regards, Terry
  14. Tharper

    WW1 Thornycroft restoration

    Hello Steve, Sorry to take so long to reply. I use Pine for the patterns. Its cheap and is easy to work with. Pine use to be very popular in the old pattern shops. You could also use Cherry or Mahogany but I find both too costly. I had one Mahogany pattern that was professionally made. Unfortunatly they did not fill the grain so when the pieces were cast using Petro-bond sand the castings picked-up the nicest wood grain! Yes, the blank is made up with three layers. The bottom and top layers each have 8 wedges (2 wedges per quarter). The middle layer is made from 12 wedges (3 per quarter) This provides overlaps of the glue joints and a bit of extra strength. I seal the patterns with a coat of shellac then prime and paint with automotive enamel from spray cans. Another trick is using pinned or removable pieces in your core boxes and patterns. Its a great way to deal with the odd item that projects from the piece and could make life dificult. Below is the pattern and core box I made for the oil pump drive housing - to the left are the remnants of the original. The orange disk visible on the inside of the core box is a for the rased boss that acts as the thrust bearing on the finished casting. Once the core box has been filled a pin is removed and the disk slides out with the core. Here is the core fresh out of the core box. You can see the disk still in place. It will be removed and the core baked. Here you can see the core in place and the impression left by the removable disk - this will form the rased boss for the thrust bearing. And.... the finished casting bolted-up for a trial fit. I hope this helps! Best regards, Terry
  15. Tharper

    WW1 Thornycroft restoration

    Hello Barry, I will be brief because I don't want to steal Steve's thread and...I want to see more of the work on the Thorney! Anyway... yes the foundry is a homemade backyard/partime commercial setup run by my friend Peter Grant of Odd Duck Foundry. He started it as a hobby but now cast parts for nuts like me that the big foundries wont take on. He can do alum. Brass, bronze and Iron. The furnace is powered by waste oil. Most of the pieces he has cast for me are bronze. Here is the result: This is the assembly for the upper water manifold. The pipe is 1-1/2 diameter". We have also cast the components for the bronze intake manifold which, as per the original, is a built-up component. I have yet to finish machining the castings. The only limit to what Peter can cast is his crucible size. In regards to the plates. I use spray can automotive enamel. Once cured I wet sand with fine wet/dry paper wrapped around a smooth piece of wood. Use no pressure...just let the paper do the work. I also add a bit of dish soap to the water. NOW BACK TO THE THRONEY! I NEED MY DAILY FIX!
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