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Electric Traction Engine

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JasonB28/03/2019 17:50:59
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Depends if you want it to look like areal engine in which case all that lot should be riviteddevil

Button heads may be a good compromise

Paul Kemp28/03/2019 18:02:53
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Ron,

As Jason says horn plates are normally rivetted, in fact on FS engines they are often an upward extension of the firebox sides and the centre 'rivets' you see are actually the knocked up ends of the boiler stays, the ones around the edges being the rivets holding the boiler plates together. On models it is normal to have a small number of screwed fixings (6 or 8 per side) and button head Allen screws are good for that, the socket can be filled after fitting if you wish and the rest are dummy rivets. I am pretty sure some of the kit manufacturers just advocate loctiteing plain shank round head rivets in suitable clearance holes. With yours being cold this would be fine.

Paul.

Ron Laden28/03/2019 18:02:58
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Posted by JasonB on 28/03/2019 17:50:59:

Depends if you want it to look like areal engine in which case all that lot should be riviteddevil

Button heads may be a good compromise

That just reinforces something I thought the other day, I need to spend an hour with a full size engine armed with my camera.

JasonB28/03/2019 18:18:10
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Regarding joining the studs and nuts that only tends to be done on the fixings that hold the cylinder to the saddle as it would be hard to get hold of the studs to remove them if needed as you can't slip the cylinder up off of them due to their radial layout. All other studs would just be screwed into one part and loose nuts used. having said that you can make up your own "bolts" by Loctiting a nut onto a stud for ease of assembly in which case 638 that you mention will be fine.

Ron Laden28/03/2019 19:30:07
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Thanks Paul and Jason

Ron

Ron Laden29/03/2019 08:08:24
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I see socket round head screws advertised but are they true round heads or actually button heads. In one or two images I,ve seen they do look to have a true round head where as button heads dont. If they are available wouldnt they be a better representation of a round head rivet..?

Edited By Ron Laden on 29/03/2019 08:14:40

Ron Laden29/03/2019 20:11:16
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The Chinese gear set arrived today which when you consider they were ordered only seven days ago, thats pretty impressive. They look good, I have checked each one of them and cant find any issues with them at all. They are 15mm thick so there will be a fair bit of turning to reduce them though I havnt figured out the best approach for the 80 tooth yet. I could have got 10mm gears which would need much less machining but they were almost twice the price so the cost was the decider.

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Edited By Ron Laden on 29/03/2019 20:13:41

Edited By Ron Laden on 29/03/2019 20:29:46

Ron Laden30/03/2019 10:31:00
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On the final drive I am thinking of doing away with the 25T gear which is fixed to the 50T and have the 50T mate with 80T. The 12T which is at the 10 o,clock position on the 80T is the motor drive gear and all the other gears run back to the crank from the 80T. My thinking..? well using the 50T/80T instead of the 25T/80T will half the speed back at the crank plus changing to all Mod 1.5 from 1.5 and 2.0 gear placing/mating has changed. Thats my thinking at the moment anyway.

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Ron Laden30/03/2019 15:10:38
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Reduced one of the gears down to 6.5mm, easy enough to do but a bit long winded on a mini lathe.

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JasonB30/03/2019 15:13:59
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I quite often saw them down the middle then you get two gears for your moneysmiley

Ron Laden30/03/2019 15:23:44
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Posted by JasonB on 30/03/2019 15:13:59:

I quite often saw them down the middle then you get two gears for your moneysmiley

Machine sawn Jason..?

Ron Laden31/03/2019 08:55:11
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Well the gear teeth are certainly hard and more than I expected, I tried cutting one of the small gears with a hacksaw (new blade) and it wouldnt look at it so its probably back to the lathe.

JasonB31/03/2019 10:08:13
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Handsaw as they are too thin to hold to machine saw.

Though the ones I have bought in the past did not have the dark heat discolouration around the teeth so looks like yours have had some sort of heat treatment.

Ron Laden03/04/2019 10:36:15
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Made a start on the bearing set, a couple of firsts for me, first time setting up and using a four jaw and the first time I,ve done any boring on the lathe, it went well.

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Ron Laden03/04/2019 20:47:04
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I was surprised to see that for reamers above 3/8" the recommended hole size is 1/64" below finished size, I didnt think it would be that much to be honest. The first pair of bearings I am working on are for the axle and the axle is from 16mm ground steel bar. I do have a 16mm machine reamer but I am thinking of boring to size using the axle as the gauge and for this I have allowed 0.010" for finishing to size, just waiting for the bar to arrive.

JasonB03/04/2019 20:50:44
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That is what I do 99% of the time for anything 8mm or larger, just bore to the fit you need using the male part as a gauge.

Boiler Bri03/04/2019 21:18:20
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If you use a reamer to get to size are you not going to end up with a larger hole? Unless I have missed something and your using an adjustable reamer?

All my fixed reamers are over size when used.

Only a small amount.

If you want to borrow an adjustable one I can lend you one?

Bri

Paul Kemp03/04/2019 22:26:38
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Posted by Boiler Bri on 03/04/2019 21:18:20:

If you use a reamer to get to size are you not going to end up with a larger hole? Unless I have missed something and your using an adjustable reamer?

All my fixed reamers are over size when used.

Only a small amount.

If you want to borrow an adjustable one I can lend you one?

Bri

Well generally for what Ron is trying to achieve you need a bit of oversize or undersize somewhere if a shaft is going to enter and be free running in a hole. If your reamer makes the hole exactly 16mm and the shaft is exactly 16mm then a decent running fit is unlikely. Professional reamers are made in a variety of tolerances to allow for this, the general hobby reamer will make a hole with a little clearance in which a shaft of the nominal size will run. Remember oil takes up space too so it's always good to leave a bit for it to do its job. Size for size is not a good free running fit. If you want to make the hole and shaft a press fit then you really have to look at tolerances. For general running fits a general purpose reamer is fine. I have just made a 1 1/8" hole into which I need to press fit / shrink fit a bush. I used a standard machine reamer for the hole as an easy, quick way of making a hole that is basically round with a good finish, saved setting up the boring head. I will put the interference on the OD of the bush when I turn it after measuring the hole.

Paul.

Ron Laden04/04/2019 08:09:07
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Posted by Paul Kemp on 03/04/2019 22:26:38:
Posted by Boiler Bri on 03/04/2019 21:18:20:

If you use a reamer to get to size are you not going to end up with a larger hole? Unless I have missed something and your using an adjustable reamer?

 

All my fixed reamers are over size when used.

 

Only a small amount.

 

If you want to borrow an adjustable one I can lend you one?

 

Bri

Well generally for what Ron is trying to achieve you need a bit of oversize or undersize somewhere if a shaft is going to enter and be free running in a hole. If your reamer makes the hole exactly 16mm and the shaft is exactly 16mm then a decent running fit is unlikely. Professional reamers are made in a variety of tolerances to allow for this, the general hobby reamer will make a hole with a little clearance in which a shaft of the nominal size will run. Remember oil takes up space too so it's always good to leave a bit for it to do its job. Size for size is not a good free running fit. If you want to make the hole and shaft a press fit then you really have to look at tolerances. For general running fits a general purpose reamer is fine. I have just made a 1 1/8" hole into which I need to press fit / shrink fit a bush. I used a standard machine reamer for the hole as an easy, quick way of making a hole that is basically round with a good finish, saved setting up the boring head. I will put the interference on the OD of the bush when I turn it after measuring the hole.

Paul.

As I mentioned once I have the 16mm ground bar I will use that as the gauge and bore to achieve a good running fit, dont want to use the reamer in case it cuts too big. I am using ground bar for the axle, crankshaft, 2nd and 3rd shafts so they set the size and associated parts I will machine to achieve the type of fit needed, well thats my plan.

Ron

p.s. Thanks for the offer of the reamer Bri but hopefully I wont need one.

Edited By Ron Laden on 04/04/2019 08:14:31

Ron Laden17/04/2019 16:18:07
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Have been working on the loco but back to the engine and the ground steel bar arrived. I cut a piece and made up gauge for the axle, managed to bore to a nice running fit. The gauge will come in handy as I can mount it in a collet and use it to centre the part to the RT. Next job is to machine the tear drops which I havnt quite worked out the best approach yet, the angles tapering to the top are I think around 12-13 degrees and I need a 3mm wall thickness around the bottom half of the hole....still thinking on it.

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