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Thread: Aveling I.C. Model Roller
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10th Oct 2017, 09:27 AM #1Member
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Aveling I.C. Model Roller
G'Day All,
I started the build of this 1-1/2" scale Aveling model roller (designed by Edgar Westbury, circa 1938) early 2013. I found a set of copied original drawings from the Model Engineer magazine of the time, while looking for similar drawings for the Aussie built McDonald roller. The original drawings were drawn to be used with a set of castings that were available in the UK & apparently still are available.
I scaled up every sheet that had a drawn component on it & worked out a scale for each drawing from a dimensioned size. Then I drew a set of working drawings to enable all components to be either machined from solid stock or to be fabricated. This took three months to complete & finished up with 65, A4 pages of detail drawings.
As the camshaft is driven via two small spiral gears & this was the first problem to be sorted out. If I could not produce these gears the project would not proceed. Fortunately, I was able to make contact with a brilliant Canadian Modeller, Mr. Allan Suttie who steered me in the right direction as to how to make the two jigs required to enable the gears to be turned by plunging a formed HSS tool bit to depth, producing one tooth groove at a time.
This worked better than expected after a bit of trial & error.
To obtain a suitable tool profile a "hob" like cutter of 0.6 module was made to cut a spur gear to be used to grind the tool bit to a suitable profile.
DSCF3862.jpg
The two jigs (one for 60˚ & one for 30˚) shown below are held in a chuck & presents the gear blank in a position that enables a groove to be cut around the gear blank surface at the correct angle. It's a rather strange motion that the blank rotates through but, it worked.
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The final gears & a little jig to test run them.
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Once happy with the timing gears the crankcase/water jacket was started.
The material used for the crankcase was two pieces of 145 x 105 x 25, 6061 Aluminium. The internal cavities milled using both standard & bull nose end mills. A note here, all machining is manually done.
DSCF4075.jpg DSCF4077.jpg
Regards & will continue,
Don.
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10th Oct 2017, 10:12 AM #2
Don welcome to the Forum. I will be looking at this thread with interest as you proceed. Great text and photos!! Isn't it great how "strangers" are willing to help you through difficulties we run into.
Just do it!
Kind regards Rod
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11th Oct 2017, 01:03 PM #3Member
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G'Day All,
Thanks to all those that send a like for this thread.
To continue with the crankcase, both sides of the c/case were held together using 14, M3 c/sunk head screws positioned around both the internal & external contact surfaces. The bores for the cylinder sleeve & the bearing housings were then finished. The cylinder bore was done first.The centre positions of all bores were set concentric using a wriggler & dial indicator. The c/case was then milled to final form.
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The two crankshaft bearing housing were completed next. One was a straight forward turning & milling job.
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The housing with the cam gear housing was a different matter. Rather that try to make it in one piece, it was made as two parts that when fitted together & hopefully would appear as a casting. With the addition of a little liquid metal & a good sanding hopefully this will be the case. The housing being attached with two, M3 socket head screws.
DSCF4513.jpgDSCF4517.jpgDSCF4518 (1).jpg
The crankshaft is made from a piece of 4140 steel & was turned as a whole part between centres.
DSCF4175.jpg Marking out of the main lengths of the webs & journals.
DSCF4177.jpg First cut to rough out the crank pin.
DSCF4180.jpg Crankpin roughed out.
DSCF4183.jpg Crankpin to finished size.
DSCF4181.jpg Tools used to turn the crankpin. The tool on the right is a piece of key steel, milled to house a piece of abrasive grinding stick. The abrasive was held in place with a finger type clamp & a liberal amount of 24hr araldite. As this tool only had to improve the surface finish, it held together long enough to achieve the desired results. The old HSS boring bar was used to relieve the webs around the crankpin.
DSCF4195.jpg To turn the journals & reduce the possibility of the crank flexing, a fitted piece of aluminium was placed between the webs & held in position with a cable tie.
DSCF4199.jpg The crank was then milled to produce the two counter masses.
DSCF4206.jpgDSCF4208.jpg The finished crank. The threads are M10 x 1, both screw cut. The journals are both Ø12.5, the crankpin Ø11.
This may be a little point of interest. For some time now I have been using pressure pack etching primer paint as a making medium, for two reasons. Firstly, if it is put on lightly, a good line can be scribed into it & the great advantage is that it is not removed by cutting fluids/oils. Secondly, it is readily available. I found in my area that small quantities of marking medium are on longer available, a five litre bottle was totally over the top! I use both black & grey primer. The colour depends upon the colour of the metal to be machined.
Regards,
Don.Last edited by Don@2480; 11th Oct 2017 at 01:06 PM. Reason: Remove duplicated image
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13th Oct 2017, 10:25 AM #4Member
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G'Day All,
The cylinder head was the next part to be made & started as a block of 6061 Al.
The head is water cooled & has an internal combustion chamber that also provides entry positions for the valves. The third image shows this feature. The cover plate & nut are simply to seal the water gallery on the outer side of the head.
Other engines that I have built, have had the valve seats as an integral part of the head or as inserts & I have had trouble trying to get the valve & seat to make a total seal without a lot of valve lapping. I decided to try a different approach & made the valve, valve stem/body & seat as "cartridge" type insert, so that the valve & seat could be lapped together & the valve cartridge could be assembled & then inserted into the head as an assembly. Happily this worked very well. The cartridge is sealed with a gasket under the top flange.
The cylinder sleeve is made from 4E cast iron & was a straight forward turning & drill job. To hone the cylinder to final size I had to make an adjustable hone by turning an arbor with a No2. Morse taper to expand the hone sleeve. Two hone sleeves were made one of soft brass & the other aluminium for finish lapping. The final lap was done using 1200 grit lapping paste & kero. The arbor has a piece of 1.5mm sheet let into it to act as a key to stop the sleeve spinning. Next time I make a hone like this, I will add a threaded section behind the large diameter of the taper to aid removal of the sleeve.
The original drawings had a spark plug size that was far out of scale for the size of the engine. I have used miniature plug with a 1/4" x 32 tip thread. Big difference when compared to a standard plug.
Regards for now,
Don.
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13th Oct 2017, 11:04 AM #5
Don the pics didn't load. You may have to do them again
Just do it!
Kind regards Rod
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14th Oct 2017, 03:24 PM #6Member
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G'Day All,
I tried to post yesterday, but some thing went pear shaped & it did not come up. Try again.
The cylinder head started as a block of 6061 Al. Turned the threaded spigot first, then completed the milling & drilling.
DSCF4242.jpgDSCF4248.jpgDSCF4268.jpgDSCF4269.jpgDSCF4265.jpg
The head is water cooled & has a combustion chamber (forth image) with a valve on either side of the chamber. The hole in the top of the face of the head (third image) is the inlet port. The exhaust port is in the bottom surface of the head. When assembled the piston comes to within 0.5mm of the head. The nut & flange are to seal the water gallery on the head's external surface.
The valve cartridges have been modified slightly from the original design & I think a good improvement to positioning a very small valve seat in the head. I have had problems with trying to get small seats into heads & stay square to the axis of the valves on previous engines.
The cartridges contain the valve, seat, body & spring & are sealed with an oil jointing gasket under the flange. The the valve seats are cast iron. The valve stems & heads are silver steel. Heads being silver soldered to the stems.
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The cylinder liner was simply a turning & drilling job.
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The honing tool consists of parallel arbor & a No2. Morse taper to expand the hone. The taper has a 1.5mm piece of mild steel sheet in it the stop the hone rotating. What should have being made into the arbor is a threaded section at the large end to remove the hone. The brass hone was used for the initial hone & the aluminium hone for finishing. The finishing abrasive was 1200 grit paste & kero.
The original drawing called for a standard sized spark plug, which is way out of scale. The plug used is a miniature plug with a 1/4" x 32 TPI thread & suits the application far better. Not much of it when compared to a standard plug.
DSCF4294.jpg
Regards,
Don.
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17th Oct 2017, 11:17 AM #7Member
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G'Day All,
The carburettor body was next to be fabricated. Again I wanted the body to look as though it was cast, so the various components were machined, assembled & silver soldered together. The silver solder used was 45% silver, expensive, but so good to use. The carby body has a spring loaded choke type valve that sits over the main section of the body & is activated by the engine vacuum (2nd image) to open a series of ports in both the sleeve & body. The finished carby shown in the third image.
DSCF4503.jpgDSCN0405.jpgDSCN0402.jpg
The exhaust & inlet cams were milled with the aid of a boring head & dividing head. The boring head being set so the tool & cam blank only made contact on one side of the blank. The dividing head was rotated in 5 degree increments, with the tool being fed down the blank width to cut the side of the blank. This process continued until a radiused surface was left unmachined that a radius could be filed to suit the dwell of the cam at fully open position. The sides of the cams did finish up with a larger than required radial lift face, requiring filing to form a flat lift so that the valve opened & closed as required. The cams are both made from 4140 steel & will be heat treated. The cam shaft is a length of Ø6 silver steel, with the cams attached to the shaft with two M3 grub screws that align with small dimples drilled into the shaft. This sounds a bit dodgy for a cam shaft but, has worked OK.
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The big end bearing is made form phosphor bronze. The bore was turned a little under size & then was scraped to fit the crankpin. The two small tubes are the oil pickup tubes for the bearing lubrication.
DSCF4552.jpgDSCF4573.jpg
The piston rings are made from 4E cast iron. The Method that I used to make the rings was found in a Model Engine Builder magazine, where the rings are turned oversize for both the OD & ID. The rings are fitted to an arbor & then slit with a 0.6 mm slitting saw. The rings are put onto another arbour that is turned to the diameter of the piston ring groove & compressed so that the gap from the slitting saw is completely closed & the rings are then turned to the diameter required. The working ring gap is filled to size after the final turning.
DSCF4172 (1).jpgDSCF4165.jpg19.03.2014.jpg
All the parts of the engine prior to assembly.
DSCF4610.jpg
Regards,
Don
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20th Oct 2017, 09:28 AM #8Member
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G'Day All,
Final images for the Aveling engine.
Had a few problems with the incorrect choice of material for the fixed ignition point. I initially made the fixed point from an M3, 316 stainless steel bolt. The spark eroded the contact face in no time & caused a scale to form on the contact face that greatly inhibited the spark conduction, causing the engine to run very erratically. A new fixed point was made by silver soldering a tungsten point removed from an old set of ignition points to a brass thread. Problem solved.
Fuel was also a bit of a problem. Firstly, I tried a commercial fuel produced for four stroke, glow plug aero engines. This stuff fired OK but filled the garage with smoke & set off the smoke alarm in a couple of minutes. 91 octane petrol made the engine run rough, 96 octane made it run too hot. A shandy of 50-50, 91 & 96 works well.
Images below are the engine being valve & ignition timed & general images.
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The image is a bit dodgy but its an old video camera that I borrowed.
Thanks to everybody that have responded to this thread. Much appreciated.
Regards,
Don.
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20th Oct 2017, 12:10 PM #9Senior Member
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Got to be happy with that Don. Good one.
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20th Oct 2017, 01:44 PM #10Diamond Member
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Don
I, for one, have admired the marvellous skill & precise workmanship that you have put into this project.
Its an admirable piece of work, & the resulting working model is very satisfying to watch.
regards
Bruce
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22nd Oct 2017, 12:52 AM #11
Hi Don,
Very nice work, runs and sounds quite good.Best Regards:
Baron J.
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22nd Oct 2017, 09:51 AM #12Golden Member
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G'day Don,
You've done an outstanding job on your engine and the video of it starting and running so smoothly is a testament to your skill.
I've been working on an engine myself since 2013 but my progress is dwarfed by yours.
I find the method you used to make the skew gears particularly interesting and one I might try replicating When the time comes.
Thank you for this thread.
Cheers,
Greg.
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23rd Oct 2017, 08:39 PM #13Most Valued Member
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Nicely done. Any idea what it's maximum RPM is?
Chris
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26th Oct 2017, 12:22 PM #14Member
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G'Day All,
Thanks again to those who have liked & given nice comments.
Chris, I do not know what the maximum RPM of the engine is, as the electronic tacho has had a burn out. The highest engine speed in the video is at half throttle. I was not brave enough to take it any higher as the RPM was fairly high at this throttle setting.
Greg, if I can assist with any information for the spiral gears that you require, just give me a yell.
After the engine was running to requirements, I started on the differential & its gears. I thought that cutting bevel gears at home was going to be a rather large challenge. However, after reading the bevel gearing section of Ivan Law's book "Gears & Gear Cutting", the process was fairly straight forward. A HSS tool bit was ground to the form of the appropriate gear cutter & then mounted in a purpose made fly cutter.
Aluminium gear blanks were used to make bevel gear & pinion test gears prior to making the cast iron & bronze gears.
The first image is the test blank, being used to firstly check the indexing calcs. Second image is a cast iron gear being cut, then the test & finished pinions.
DSCF4000 (1).jpgDSCF4037.jpgDSCF4011.jpgDSCF4017.jpgDSCF4031.jpg
The diff spider has a 95 tooth 1.0 module spur gear attached as the diff driving gear. To cut this gear a "hob like" cutter was turned to form on the arbor that it was to mounted in the mill on. The steel used for the cutter is 0.75% carbon tool steel. The teeth being relieved & the finished cutter after heat treatment. The spur gear blank was mounted on the diff spider & the teeth cut using 0.5 mm depth of cut during roughing & 0.25 depth for finishing.
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The finished differential.
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Another gear & pinion have been machined to be used in the transmission.
Regards,
Don.
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26th Oct 2017, 02:25 PM #15Senior Member
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Nice work Don.
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