Building 1/4Scale Redwing Hit and Miss Engine

Went in to Rotagrip in Birmingham and collected the set of soft jaws for my new Elliot chuck and also picked up a set of small Imperial Broaches. I thought I had bought Metric broaches from them previously so happily collected the Imperial ones. Till I arrived home and found I already had an identical set.

I had bought the gears ready made from HPC but I knew they would want quite a bit of machining to bring them to correct thickness and have the correct bosses on them. What I started with can be seen below.

Fitted the jaws in chuck and found a suitable diameter bar on which to clamp the jaws to be able to bore them to hold the small gear. Bored 3/16” deep and a tight 1” diameter. Put gear in jaws and tapped down then did a quick sanity check with a drill blank in tailstock and checked it passed into the bore in gear. Faced off lot of material off down to 1/2” thick, then machined 0.750” OD boss on front which took the gears down to 1/4” . Drilled out to 15/32” then reamed to 1/2”.

Another steel bar to clamp the jaws on and then bored out to 2” dia for the camshaft gear. This gear came with a boss but this all needed to be machined off and the gear again bought to ½” thick.

Machined a 0.750” OD boss on front which took the gears down to 1/4” wide. Drilled out to 15/32” then reamed to 1/2”.

The timing gear required a 40thou deep recess in the back face of the gear and I really struggled with this, both to pick up the position and then to machine it. I made a trepanning tool of sorts with which I was able to start a groove but then tried various tools until I had a reasonable looking groove with sharp edges. I’m afraid positioning was carried out using a 6” rule.

Timing gear was then moved over to the mill and clamped in vice, ½” dia drill blank put through the bore and this was used to get centre of bore to drill and then ream to 0.156” for the ignition stud.

The crank gear was set up on the arbour press and the keyway broached. The keyway set comes with a single shim but this was not enough to get the required depth and had to make a further 20thou shim to get to correct depth.

Now moved onto the Timing Gear Shaft. Did not have any hex bar so started with chuck of 5/8” diameter bar. Because I had around 2.5” sticking out of the chuck I had centred the bar and was using the half centre in the tailstock. All appeared well until I check the diameter and found 2 thou small in diameter at the tailstock end. Could not see why and cheated with a file to finish off to size and then polished shaft. I do not posses a grooving tool and used hacksaw blade in a parting tool to provide the thread relief before using 5/16”-24 unf die for the thread. Parted the bar off and took to the mill to put the hex head on the end using ER32 hex collet block.

This went well so changed to square collet block to put the slot and hole in the end. Set it all up and used 0.125” slot mill to put the slot in. Had done around four slow passes, when CRUNCH. Turned off mill and could not initially see what had happened. Then realised I did not have two little “D” shapes on end of the bar. The bar had rotated in collet chuck. Not surprising when I checked and found I had only done it up by hand, I had forgotten to clamp up.

Start all over again. But I though it might pay to check why the Myford was cutting tapered first. I know last year I had turned a test bar and all was good from the levelled point of view. So out with 2MT test bar and put this between spindle and tailstock centre. The tailstock appeared to be out by around 1.5 though offset to front of lathe so I corrected this and also checked/adjusted all gibs then started again. It still appeared to be cutting tapered when the tailstock was in use, pulled tailstock out and all would turn okay and parallel. I have absolutely no idea what to do about this or what the problem may be.

Any way second gear shaft produced in about half the time. As I write this I have just realised I have missed one tiny detail and that is a small dimple is required on the shaft.

I made two of these as well Colin! I damaged the D shaped sides of the slot when I did the threading, the die caught and snapped one off!

Wow Ian,

You are going along way quicker than me.

I still have to make a crank, do all of cylinder head, carb and exhaust, and machine the flywheels and governor. I have the material but not too sure how my silver soldering will go. I have not really done any in the past. The odd couple of bits have not turned out brilliant.

Couple of quick points: 1) I cannot see a locking screw for the timing shaft, 2) Have you used a locking screw on the crankshaft pulley, there is not one shown on my drawings.

Colin

Ian,

A quick question. Looking at the plans am I correct in saying that the 0.250" brass ignition stud is pressed through the insulation collar and through the hole in the gear such that it just presses on the oilite bush and so completes the connection.

Thanks,

Colin

Edited By Colin Heseltine on 26/02/2023 10:40:35

Hi Colin, I’ve spent a fair bit of time on it lately (maybe too much!) to answer your questions

I haven’t got round to drilling the timing shaft locking screw.

There is a locking screw on the crankshaft pulley

And yes the ignition stud goes all the way through to the oilte bush.

Just wondering what do you need to silver solder?

ian

The ignition lever sleeve is silver soldered which I've done. But the crank will be built up rather than using casting. So the crank shafts and big end will be silver soldered into the webs. The ones I was given with the engine are both built up but just pinned and the shafts have all moved in the webs.

I still have to drill the timing shaft locking screw and it looks as though my plans have missed the crank pulley locking screw. I also found an error for the timing screw. The dimple for the locking bolt was shown to close to the bolt head.

I have done the insulation sleeve for the ignition stud and fitted that and the stud and also done the contact stud and its bushing. Need to make nuts and source spring.

Colin

Moved onto Timing Lever. This is a small brass casting which is quite awkward to hold. First it was cleaned up with a file and sharp edges removed. Could not hold it my standard 3 or 4 jaw chucks used on the Myford, but I have a Myford spindle adaptor to be able to fit my M14 x1 threaded chucks from the Cowells lathe. The best option I found was the self centering 4 jaw but I still needed something to space it away from the chuck to leave face clear to machine. Found a suitable Joey block. I needed to leave this in place whilst facing so couple of pieces of tank tape to hold in place. This was faced on both sides to 0.188” thickness.

If anyone else does this can I suggest you face both sides to a larger diameter than I did. The rear face which mates against the casting was held clear by 15 thou or so and had to be filed and also the inside face needs taking right up to the bottom of the stick out for the timing stud. If you don’t do this you will find as I did that the cam will not rotate. Again, a bit more filing. I started drilling the casting with the Joey block in place and removed it just before the drill broke through. Hole then reamed.

The thin steel sleeve is then silver soldered into the casting. Bit dubious about this but it appears to be held okay but need a bit more tidying than I had hoped.

With the sleeve silver soldered in it was then possible to fix to a 3-2-1 block and clean up the top and sides of the boss on the casting through which the small insulation bush and contact stud are mounted.

Aligned ready to drill and ream using two squares.

The oilite bush was shortened and then pressed into the timing gear. The insulation collar which is a firm press fit on the boss on the timing gear was next. I found I had some 1.004” diameter nylon/plastic bar and this was quickly made and the edge drilled for the ignition stud. Pressed this on the gear with the two holes aligned and then tapped the ignition stud into place. This passes through the collar and the boss on gear and is in contact with the oilite bush. I still had the soft jaws in the big lathe so returned gear to soft-chuck and then skimmed the proud edges of the ignition stud. The cam came next. I had to thin a piece of steel down to the required 0.188” t hen left it setup in the vice whilst marked out the cam.

The centre was then bored out. The steel then removed and excess cut off. Then used mill to bring down to within 1/16” of scribed line. Then used the die filer for its first proper job and shaped the cam. Back to the mill and centred on piece of bar then drilled and tapped 4-40 UNC for locking screw. This fits directly on the oilite bush.

Edited By Colin Heseltine on 02/03/2023 16:01:50

Edited By Colin Heseltine on 02/03/2023 16:05:22

Edited By Colin Heseltine on 02/03/2023 16:08:58

Decided I now had to bite the bullet an attempt to make the crankshaft. Two pieces of steel 0.625” x 0.375” by 2” long were cut and then super glued together. Into the mill and squared off and faced to length. Crank and big end centres marked with centre drill then drilled through in increasing sizes till just short of the required 7/16” and ½” diameters. Both holes reamed.

Crankshaft form PGMS cut to length and centred, big end cut around 0.125” over length. I also decided to make a spaced block from same material as the crank webs 0.540” thick. This used to ensure the two webs could be pressed against each other and keep correct spacing.

I had a spare pair of webs which had come with the engine so I reamed out the 1/”2 diameter hole and used these as supports for the outer ends of the crank shaft.

Now to the silver soldering. I first rang Graham Corry from Alyn Foundry and had a chat to him about silver soldering and then reviewed a video he had sent me a few pages back.

I set up the hearth on my wooden bench in the garage and put some heat bricks around the outside for extra protection. Cleaned all parts with acetone. Using HT5 flux I pre-fluxed the inside of the webs and slid them on the crank and big end. Slid them along to close to final position I then painted the made centre of big end with Tippex to prevent solder adhering here. Little more flux in all the countersink areas. Then cut 2 off 1” and 2 off 1.5” length of 1.5mm silver solder. These were then curled up into ‘C’ section shape and one put on each outer end of the big end and the larger one on the inside of each crank webs on the actual crankshaft. This was followed by bit more flux on each to hold in place.

Final check that the webs were in correct position and tight against the spacer, correct length of crank sticking out, ensuring the spare webs were on the ends of the shafts and all was ready.

Fitted the big burner to the torch and started by preheating the ends of the shaft and gradually moving towards the centre. I had turned the light off above me and could slowly see the colour changing. The flux was bubbling and changing so I now concentrated on the webs, big end and the inner section of the crank and suddenly it happened. The solder melted and did its stuff much to my amazement. I though I could see one slight gap so dabbed fluxed rod on it, looked okay so turned off heat and went and had lunch.

After lunch all was cool, looked reasonable so into jar of citric acid now for overnight and have proper look tomorrow.

All looks like the solder has all flowed to where it should and minimal amounts where it shouldn't so you won't have much to clean up

Jason,

Thank you. I’m hoping it is all okay. Will leave in pickle overnight. Hopefully it will not need too much cleaning and isn’t warped. It’s my first proper attempt at silver soldering so reasonably pleased so far.
Colin

Pictures after overnight in Citric acid and clean up with brass brush and some 1200 wet and dry.

Next job to clean up webs and remove central waste portion.

Into 5C collet chuck on Myford and the big end stick out faced flush to the webs.

Moved over to mill to remove the centre after first having hacksawed the majority out.

Final Result

Was going to start the keyways when the DRO display on mill appeared to self destruct. Need to talk to supplier on Monday.

Very helpful supplier put me on to the technical man at Fagor. 10 minutes of his time and he had it fixed. Somehow I had set the system into Reference Mode.

Couple of key presses to exit and all okay.

Whilst waiting to get mill DRO sorted jumped across to Colchester and turned the Governor Arm Shift Collar. I had correct size material in stock so just had to grind a 0.130” wide tool to cut the grooves. It actually worked quite well.

With the castings I had received one partially machines flywheel casting and one unmachined casting, both with many years of rusty brown colour on them. The machines one had the perimeter, sides, and bore completed. I needed to clean this up first to check on dimensions. It came up very nicely much to my surprise. The other casting looked quite rough around the perimeter and one boss was a little offset to say the least, but the spokes were very good with no movement of the two haves of the mould. Craned the 12” four jaw onto the lathe and proceeded to spend at least an hour trying to get the casting level and central.

Used carbide tipped tool to get underneath the skin and took the face down to dimension and then faced the boss. Boss then centred and drilled in steps to 0.4688”.

Could only get a very small boring tool in and very slowly bored out to 0.5”. Could now remove from the 4 jaw chuck and switch back to the 3 jaw. I had made a mandrel from a 0.875” piece of barstock and turned to 0.5” sand threaded the end ½” UNF and also centred the end. I hoped this would be solid enough for turning the perimeter. It ran true and I was able to take the perimeter down to approaching size but there was quite a dip on one edge. Before I went any further, I brought the side to dimension to reduce the area of the dip. Had I continued as I was I think the flywheel would not have tidied up until below size.

I could now compare the two flywheels and decide which to use on which side of the crank. The original one was to be on gear side and so this went onto a expanding mandrel to finish of the bosses to correct diameter and length. The other flywheel then mounted and bosses bought to size.

Both flywheels polished up well and the engine now looks a little more like it should.

You look to be making good progress Colin, my drawing didn’t mention silver soldering the bush to the sleeve it just buts up against it.

Any way now I have sparks ( see John Purdys Red wing post) I just thought I’d see if we had life. So I spashed a bit of petrol in the plug hole and after a few spins it fired up for a couple of turns. So I rigged a temporary fuel tank up and after a fair bit of adjustment to the mixture screw it fired up and ran ok but it was tricky setting the mixture.

As I was happy with the ignition timing I rechecked the valve timing and it was out so I set it as specified and pinned the cam. I think the cam had moved.

After a bit of trial and error I’ve found the best position for the mixture screw and it starts easily and runs very smoothly. I ran it without any water as I’m waiting for the oiler kit and even after ten minutes the cylinder was just warm .
I just need to sort out the correct nuts and bolts, finish the fuel line, tidy the wires then paint!

Ian,

Great to hear yours is a runner. It will be some time before I get that far. Currently doing slots in timing side flywheel, then need to broach keyways and drill tap for locking screws. Next step will be governor arm and latch out bars, followed by exhaust push rod.

Colin

The keyways on the crank are 0.125” wide and 70 thou deep. Used a short 0.125” slot mill and ran it at around 2000rpm. Did three 20 thou deep cuts followed by 10 thou cut. Pleased with how this went.

Governor Bracket was next on the list and this was a bit of an awkward thing to hold. After a bit of clean up I managed to get it held centrally in small 4 jaw chuck and then drilled it out to 0.5”. Then mounted it on a slit arbour to machine the rear face and main diameter. Turned it about face to bore the inside face and the bore between the ears for the governor shift collar and then the 15 degree angle on the back of the ears was next. At some point I realised I had a minor issue. The interrupted cut was moving the bracket along the split arbor. I had to stop and make a new slit arbor much shorted, a better fit and with a M6 grub screw in the centre to keep it out of the way of the boring tool.

Decided to drill and ream the holes in the ears for the governor arms prior to milling the slot in the ears. Mounted on a 1-2-3 block and set it up square. I could not pick up on the bore diameter as I had a bolt through it so used the laser centre finder to pick up edges of the base and halved it. The holes drilled and reamed without any issues.

1-2-3 block then turned through 90 degrees to machine slots. The downside of using bolt and washers to hold brackets to 1-2-3 block was the inability to mill across in one go. Did each side at a time and was careful not to run the cutter into the steel washers. The other downside was that I could not drill the two 4-40 UNC clearance holes for the fixing screws. Removed from 1-2-3 block and sat it on parallel between pair of ‘V’ blocks and again used laser centre to pick up outside edges of the ears and get it square. Used 0.5” diameter drill blank to pick the center. Drilled both holes and then found 82 degree countersink to countersink the two holes. Because of the way the casting had been done the countersink covered two different heights of the base and so looks a bit unusual.

The brass casting needed a bit of cleaning up afterwards with riffler files.

Moved onto the timing side flywheel and mounted this on large arbor and mounted it vertically between pair of ‘V’ blocks. Rotated flywheel to get the two slot positions along the X axis. Picked the centre up using coax centering device on flywheel boss.

Offset each side of the centre and drilled 0.125” hole as a guide for the slots. Then offset either side of centre on the ‘Y’ axis and drilled and tapped the 4-40 UNC mounting holes for the governor bracket. Flywheel then move to bench vice and the two slots cut with hacksaw and then filed to dimension.

Ideally I wanted a pair of grub screws in each flywheel to bear on the key, but there is just not enough room on the governor bracket side of the one flywheel, but on the second flywheel this was possible.

Flywheel was stood vertically in a vice and ensued that the keyway was uppermost and the flywheel spokes were aligned vertically. The smaller vice then put in jaws on main vice and magnetic angle gauge used to set the flywheel at 10 degree angle.

Used 0.5” drill blank and edge finder to find centre and set DRO to zero in both axis. There was no way to get a drill chuck in but I did have an ER11 long parallel arbor. This was used to hold 2.9mm drill. Double checked alignment by sighting drill in front of keyway and when happy moved to location of hole and drilled through casting.

Removed drill and replace the collet and inserted 6-32 UNC taper tap. Put spindle into neutral and turned spindle by hand to tap hole.

Then ran a bottom tap through hole using Jacobs No. 0 check to hold it.

Repeated this exercise for the three possible holes.