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Member postings for Jim Nic

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

Thread: Hobbymat MD200
19/05/2019 20:42:17
Posted by SillyOldDuffer on 19/05/2019 20:19:49:

Difficult to describe why larger lathes make life easier, but they do!

Dave

For one thing, as has oft been said on here in response to the "What lathe?" question, you can make small parts on a big lathe but not big parts on a small lathe.

Jim

Thread: stamford show vandals
19/05/2019 15:03:16

Words fail me at the utter mindlessness of such destruction.

How do you motivate yourself to rebuild a layout after that and if you did I cannot imagine it would be shown in public for the enjoyment of others again.

May the culprits be severely punished, but I doubt that that will happen.

Jim

Thread: Adjustable workshop perching stool
13/05/2019 14:10:44

Looks very useful Stew, is that a lavatory seat you have on it? I manage with an assortment of 3 stools but not having the kit or expertise to weld I shall have to continue doing so.

Jim

Thread: Pressure gauge help needed please.
27/04/2019 18:14:25

Hi Bob

If you want something fairly quick there is always Jason's Jowitt engine, the complications being the shape of the cylinder block and the need to make the poppet valves and the spoked flywheels.

finished jowitt 7.jpg

More complex is the Corliss type engine, free plans from Model Engine Makers website. Complications are the operation of the valves and making the flywheel. Everything else should be a breeze for you.

corliss 1.jpg

My last suggestion depends on your budget. The Eastern & Anderson Grasshopper model from a castings set available from Polly Models for about £240 I believe.

dsc01612.jpg

Hope this has given you something to consider

Jim

Thread: The Chocolate Fireguard as designed by Mercedes Benz
26/04/2019 10:38:28

My Honda Jazz has a similar speed limit recognition system to Keith's Merc but has a display of the limit recognised by the camera. When I bought the car I thought it might be useful to have a reminder of what the limit was always on display in this day and age when limits change seemingly on a whim many times on most stretches of apparently similar road. However the display turns off after a minute or so of the car recognising a speed sign so there is no lasting reminder.

Even worse, the system can be set so that if the car recognises a speed limit sign it will not accelerate to a speed faster than that limit, which would be sensible if the car's camera and computer always correctly recognised the signs which is a long way from being the case.

The whole system has been turned off (after a lengthy trawl through a maze of menus).

Jim

Edited By Jim Nic on 26/04/2019 10:41:38

Thread: The Workshop Progress Thread 2019
03/04/2019 22:46:43

In my last post on the progress of Stew Hart's Overcrank design I had made the valve eccentrics (and the eccentric straps) which had to be fitted to the crankshaft centre section before assembling the shaft. I then thought that making up the shaft would naturally be the next operation. When I came to cut the 12mm dia bar to length for the main part I found that the exact length depended on the width of the flywheel and the output pulley hubs. Sooo the next task was to obtain a flywheel casting from Stuart Models and machine it and make a pulley and, while I was at it, a pulley for the governer belt.

flywheel 6.jpg

output 16.jpg

Then I assembled the crankshaft using my usual Loctite method but since this was a twin cylinder engine I also pinned the webs. The pins are fitted through the webs from one end, go through both the "big end" and the shaft section but stop short of protruding from the other end of the web.

crankshaft 6.jpg

And here is an assembly shot of the crankshaft in position before I had cut out the redundant pieces between the webs.

crankshaft 7.jpg

Next up I get to fit the laser cut crank return rods

return conn rods.jpg

Jim

Thread: Potty overcrank
29/03/2019 15:04:45

Well there's this one

vertical cross single 1.jpg

Jim

Thread: Scaling dimensions
25/03/2019 22:02:21

I scaled up this Mogens Kilde designed Double Diagonal engine by two by simply doubling the drawing dimensions and found that while most aspects looked OK at twice design size, the fasteners most definitely did not. Bigger - yes, but not twice as big. I actually used BA fastenings instead of the metric called for on the drawings and just chose sizes I thought would look right and took the view that for an air powered model whatever I chose would would be strong enough.

99 finished 1.jpg

99 finished 2.jpg

Jim

Edited By Jim Nic on 25/03/2019 22:04:23

Thread: The Workshop Progress Thread 2019
30/01/2019 17:16:29

I’ve not been well for a couple of months so there has been less progress on the Overcrank engine than normal.

This is the first engine I have built without the benefit of a build log or construction notes for guidance. My plan was to make the crankshaft next but luckily I had a close look at the drawings before I did and found that the valve eccentrics and crank centre bearing were on the shaft between the 2 throws.

eccentric 3.jpg

The bearing could have been made as a split shell but I couldn’t see how to make the eccentric sheaves work with a join in them. So the only way seemed to me to make them as normal

eccentric 2.jpg

and assemble them on the crankshaft before assembling and pinning the journals.

eccentric 4.jpg

Happy days, the valves seem to move as they should so now it's back to the plan and build the crankshaft.

Jim

Thread: Use of Colour on Drawings
16/01/2019 12:03:02

Jason

Firstly thanks for your consideration for the needs of your "customers".

My difficulty is sometimes visualising the shape of the part from the drawing so the addition of an occasional 3D image is welcome. The rendering of the intended result is also useful so I know where I am headed.

My preference of your options would be 1 or 2. Dimensioned in metric, on uncluttered A4 sheets in PDF format.

Jim

Thread: Forum Video Size
27/12/2018 11:29:12

The vid worked for me Ron. All you have to do now is work out how to turn the web address of it into a clickable link wink

Jim

Thread: Stockport Vacuum Engine
16/12/2018 12:11:47

Nice looking result Mike, well done.

Jim

Thread: Sourcing
11/12/2018 21:28:29

I would be very wary of cheap or free bits of metal. For use on our hobby machines free cutting metals are the best materials to start with then harder and tougher types can be utilisd when experience is built up.

Regardless of experience and machine it is always best to know what metal you are dealing with, there are some very tough machining resistant steels about.

Best, in my opinion, to bite the bullet and purchase known materials from known sources.

Jim

Thread: What did you do Today 2018
04/12/2018 15:09:07

Thanks Jeff and George.

I blacked the parts by heating to red and then dunking (a technical term) in engine oil till cooled. Best done in the open as lots of smoke results and probably a fire risk. As you probably are aware used car engine oil is carcinogenic, although I'm not sure how much you have to drink before there is a real risk, so I use clean oil. It works for me and a part I blacked 8 years ago still retains its colour so I'm happy to use the process.

Jim

04/12/2018 12:18:01

A small thing, but a win's a win.

Since I got my Rotary Table about 6 years ago I've been meaning to make a couple of clamping blocks for it. As a break from my current engine project, today I got them done.

rt clamp 1.jpg

rt clamp 2.jpg

Jim

Thread: Type of builds on this site
04/12/2018 09:26:04

I would welcome an artillery build log. Although artillery is not my thing I am always interested in how others approach modelling problems and engineered models of any subject are interesting to me.

Jim

Thread: What did you do Today 2018
27/11/2018 12:40:12

Actually yesterday, I received the laser cut return connecting rods in stainless steel for my Overcrank Engine. These rods are in effect the crosshead but they work around the crankshaft thus shortening the engine. They were produced for me by Model Engineers Laser from a paper drawing.

return conn rods.jpg

I could have made them myself but producing 4 seemed like a chore so I took the easy route.

I understand that Malcolm at Model Engineers Laser runs it as a retirement project and he tells me that unfortunately his service will no longer be available after the end of 2020. That is a great pity as his service is excellent in all respects and he is willing to work from a paper drawing.

Jim

20/11/2018 16:23:43

Yesterday I managed to break the mounting spigot of my DTI.

Today I spent some time on t'internetty trying to find a replacement spare. After a fruitless hour or so I got fed up and made one.

dti spigot 1.jpg

On the left the broken cast ali original, on the right the replacement from a bit of steel out of the bits and bobs drawer.

dti spigot 2.jpg

That should keep me going for a year or two.

Jim

Thread: The Workshop Progress thread 2018
23/10/2018 19:51:29

One step forward and 2 steps back on the Overcrank. I made the base, just a piece of ali sheet with 6 round holes for the crank bearing supports and 4 elongated holes for the cylinder block. What could possibly go wrong?

base 2.jpg

When I offered up the cylinder to the base I found out. The holes in the cylinder base were incorrectly positioned and although I could have used them the cylinder would have been 90 deg out and pointing acrtoss the base instead of along it. The correct positions are marked out in the picture below.

base 4.jpg

"Oh, pooh sticks." I said, and went for a lie down while I considered whether to scrap the base or the cylinder block. After a while when calm was restored I came up with a simple plan and plugged the M4 holes in the cylinder base and redrilled them in the correct place.

base 6.jpg

After that I made the crankshaft bearing supports. Here is the base with one shaped support and 1 blank (the third is set up on the milling machine).

base 7.jpg

For some time now I have been muttering within earshot of the Domestic Authority that I could do with somebody to talk to while I'm busy making important stuff in my "playroom" as she calls it. I have let it be known that a dog would probably fit the bill despite her lifelong objection to domestic animals making a mess in her nice clean house.

Well to day she gave in and came home with my new pet. Meet Doug:

doug.jpg

I'm not sure she is taking this matter seriously.

Jim

Thread: Given the Elbow
23/10/2018 10:07:11

Not bad indeed Eric. A very attractive flywheel and the rest of the engine looks good too. As you say, all that's left to do is get it running and post a video.wink

Jim

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