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Member postings for Perko7

Here is a list of all the postings Perko7 has made in our forums. Click on a thread name to jump to the thread.

Thread: Is this doable?
17/09/2020 11:33:39

Shape the end but leave it a bit longer, then drill a 1mm hole near the end and grind or mill away the bit you don't want.

Thread: Brass to mild steel, expansion issues?
16/09/2020 13:40:20

If the horn plates are rigidly attached (bolted or riveted) to the frames then they will all move together as one. The two different metals will try to expand at their individual rates but will be held captive by the rivets or bolts so both items will move together as a composite assembly. The different expansion rates will result in an increase in internal stress in each item and an increase in shear stress in the connecting rivets or bolts, but we are talking minute quantities at this size.

Thread: crankcase construction
13/09/2020 13:13:00

Thanks for those responses, nice work Jason.

I'm reasonably handy with a stick welder but don't have the gear for silver soldering larger objects. Thinking that fabricating with tabs and slots for accurate location, tack weld in position, then full weld, stress relieve, then machine working surfaces should provide a stable platform for further work. Have a friend who does wrought iron work, he has a suitable hearth to heat up largish bits like a completed crankcase to relieve welding stresses, but not for silver soldering.

Early days, probably won't be until next year that any metal is fabricated, but wanted to get an idea that it would be feasible. Will now start designing the bits.

13/09/2020 05:04:55

OK, dumb question time smiley. I am looking at making an engine based on the ETW design for the diesel roller described in ME many years ago. Obviously castings for this would be about as common as the proverbial. I have read elsewhere many times about cylinder and valve assemblies for steam engines being fabricated from bars and plates and silver soldered together, so what would stop the same process being used for an IC engine? Either silver solder or weld, clean up and machine afterwards. Would seem to be a lot easier, faster and cheaper than machining from solid. Any pitfalls I'm missing?

Thread: Solder ???
09/09/2020 11:19:57

Another option is to clamp a decent heat sink onto the area already soldered before soldering the next area.

+1 on the comment from Clive Brown 1 about re-melting needing more heat than the original melt.

Thread: Jobs we had as kids
08/09/2020 12:42:32

Spent about 6 months when I was about 16 working as an offsider to a milko (milk delivery truck) on Friday nights. Started about 10PM, finished about 6AM, Fascinating seeing the streets of my local area in the western suburbs of Brisbane during the small hours and witnessing some of the things that went on while most good folk were asleep. Pay was borderline on child slavery but usually managed to score a couple of flavoured milks at the end.

Spent about 12 months during first year of uni working 2 days/week at the Malleys factory in Buranda (inner southern suburbs of Brisbane) assembling oven doors and griller trays. Learnt about air tools (drills, screwdrivers, riveters etc) and assembly work in general. Also learnt the difference between dark grapes and black olives thanks to some of the migrants who I worked alongside and got to know. Pay was enough to buy my first car after 12 months which was a well-used 1949 Ford Prefect coupe ute (Aussie-built body) which in 1972 cost $120 from memory. Great little car, sometimes wish I still had it.

Thread: Door stay help
11/08/2020 07:50:27

Would replacing the nylon with a stiff felt pad (the type used for putting under chair legs) be a potentially more long-lasting option?

Thread: Australian diesel loco in 5 gauge.
28/07/2020 11:57:24

Fantastic work, really well executed. I particularly like that you have maintained the correct scale proportions of the loco body and associated fittings. Can I ask what you used for the final drive to the axles? Also it seems like it might be a bit light for good traction, have you needed to add any ballast?

I am making a Qld Railways DL Class 2-6-0 diesel but don't have the skill to make my own engine so have used a 25cc Stihl brushcutter engine. Had to make a new inlet and exhaust so it would fit inside the engine compartment. Uses a tumbler reverse for forward/reverse and an angle grinder head for the final drive. Some photos in my album but still lots more work to do adding the finer details. Currently making handrail knobs but slow progress as we are moving house so most of the workshop is currently in storage sad.

Thread: Attempting To Make My (new to me) Zyto Beautiful
19/07/2020 04:22:19

From my experience with flat leather belts, they do flap a bit at speed but rubbing on a smooth surface like the shoulder of the back gear would not cause any problem. Mine will sometimes rub on the end of a piece of steel angle forming the motor mount, other than polishing the end of the angle no harm has resulted to the belt.

Thread: Wheel Design
18/07/2020 13:43:17

Noah, will PM you with some more info. Geoff Perkins

18/07/2020 12:17:27

Contrary to Roger Best's post, there is a geometric relationship between the various arcs and lines but it is not clearly shown on the drawing. It can be worked out if you really want to be that accurate, but in my experience it is not really necessary as long as the critical dimensions (effective wheel diameter, effective width and depth of flange, and root radius) are close to the specified values.

IMO the best way to go about it would be to first face off each side of the casting to give you the overall thickness. Then turn a flat tread of 3-3/8" diameter ending in a square flange 1/8" thick and 3/32" deep to give the 3-9/16" overall diameter. Then reduce the flange thickness to 1/16" while forming the 1/16" radius at the root of the flange. Next, using a form tool and files (or just files) form the 1/32" flange radius and blend it into the root radius. Lastly turn the 3deg taper on the tread.

If you really want the accuracy of the given dimensions then I can mark up a drawing showing the relationships, but you would be hard-pressed to meet them exactly for all wheels unless you made a form tool having that compound shape.

If you are uncertain that wheels not exactly meeting the profile shown will still work, have a look at some earlier O scale and OO scale model railway wheels with cookie cutter flanges and no fillets. They still went around curves corners at high speed without derailing (at least most of the time) laugh.

Thread: Use of doubler plates for attaching pipe covering to boiler cladding
17/07/2020 13:23:30

I had a similar problem with the hood on a diesel loco which had a raised vent cowl across the top. I soldered 7BA brass nuts to the underside of the hood to take the fixing screws. It was 1.2mm galvanised steel sheet hood so relatively easy to solder. Just used my normal 40W electric soldering iron and Bakers flux with standard electrical solder. Make sure both surfaces are scrupulously clean though. I used wooden sprung clothes pegs to hold them in place as they don't act as a heat sink like metal clamps would.

Thread: Zyto Owners Only. Other Riff Raff can keep out :P
17/07/2020 13:15:53

Thanks Eric. I'm still not sure though whether there is any other underlying reason that it's not a good idea.

The problem with the shaking bench will hopefully be resolved with a new belt (I obtained some lovely new leather belting from a local shoe repairer) but I'm also considering putting in an adjustable tensioner which will hold the motor reasonably still rather than emulating St Vitus. Still don't want too much tension though. I did once get the cuff of a jacket sleeve caught on a workpiece in the 4-jaw while running at low speed in back gear. I had enough strength to prevent the rest of my arm from joining in but it was a close shave and I'm glad I wasn't running any greater tension. I don't wear long sleeves anymore when using the lathe. In the Aussie climate it's not often necessary anyway.

16/07/2020 11:16:17

Just in relation to oldvelo's final comment that 'Swinging the weight of the motor to tension the belt is not best practice' I would like some advice on why it is considered so. I have used this method on my old flat belt drive lathe for several years but if there are good reasons to change my arrangement I'm all ears.

I have found that it provides even belt tension when changing between the three steps on the flat pulleys and, with careful arrangement of the pivot point location, allows the belt tension to not exceed the power capacity of the motor. In fact I use considerably less tension as it is a useful safety net should something jam or get caught while in use. It does mean I can't take heavy cuts but it's a very old machine and I treat it gently out of respect for it's age. The only problem I have had is shaking of the bench as the motor is not rigidly held, and any minor irregularity in the belt results in shaking of the cradle holding the motor and countershaft, causing the bench to shake as well.

Thread: Moving a Hole in Cast Iron
14/07/2020 07:42:24

Depending on the size of hole, tapping it and inserting a suitable screw with thread lock could be a more secure version of Chris Evan's suggestion. I think plain mild steel would be suitable, anything else could be too soft.

Thread: Crank pins
12/07/2020 09:35:15

Thinking logically, it doesn't really matter what position they are as long as the external cranks on one side of the engine are at 90 degrees to those on the other side. The inside cranks turn the axle which in turn (pardon the pun) turns the wheels. The outside cranks are simply transferring that rotating motion from the driving wheels to the driven wheels on the other axles. Having those at a different orientation to the inside cranks should not make any difference.

Thread: Butterfly Bolt or Thumb Screw
07/07/2020 12:00:45


06/07/2020 13:18:22

Using a suitably long bolt, thread a butterfly nut onto the end until just fully engaged, silver solder in position, then cut off the head. I've used that process to make metric hex-head bolts in various sizes not available commercially. For most model engineering uses you will strip the thread before you break the silver solder bond.

Thread: We need Pi
05/07/2020 13:02:24

Maybe I'm good with numbers but I've never had any trouble remembering Pi as 3.14159 since learning it back in about 1968. 22/7 doesn't come close, and 355/113 is even harder to remember.

I can also quote from memory the registration plate number for most cars I have owned, my bank account, health care card, drivers license and several other numbers that I use with varying frequency.

I'm pretty normal otherwise......laugh

Thread: Yipee the F1 is back on
01/07/2020 07:25:20

Just finished reading a biography on Jack Brabham. Some of the comparisons between his cars and those built by Lotus, Ferrari, Maserati, etc in the early 60's are quite illuminating. Very little custom manufacture except the body. Engines were sourced from other makers, as were gearboxes, hubs, brakes, driveshafts, instruments etc, supplemented by bits and pieces made in their own workshop by Jack himself or Ron Taurenac. Racing budget of $10,000 Australian per year compared with about 10 times that for Ferrari and he still beat them hands down.

Totally different ball game today, with so much driven by expensive technology and corporate sponsorship leaving little room for private developments.

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