jem
Elder Statesman
Posts: 1,066
|
Post by jem on Dec 4, 2023 17:17:06 GMT
I have done quite a bit of aluminium casting, and have almost always made my moulds out of polystyrene or similar. This material then disappears whilst the aluminium is poured into the mould leaving a perfect casting of what the polystyrene was. This way you can make very complicated designs easy to cast. They are of cause always one offs.
best wishes
Jem
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 14, 2023 8:49:04 GMT
That was quick! I posted my pattern to Grayson castings on Thursday 7th. Yesterday, Wednesday 13, I received a message and picture of the finished job and how do I want to pay for it.
|
|
mbrown
Elder Statesman
Posts: 1,720
|
Post by mbrown on Dec 14, 2023 18:20:45 GMT
I hope the answer to the question is not "Through the nose"!
Look forward to seeing how it has turned out.
Malcolm
|
|
jasonb
Elder Statesman
Posts: 1,209
|
Post by jasonb on Dec 14, 2023 18:43:46 GMT
Well if it is anything in the region of the price I got for miken it is quite reasonable.
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 20, 2023 20:53:00 GMT
I finished off the front idler wheels. They are each clad with 7 thin steel segments. Today I started making lots of 1/8" diameter round head rivets into pointy-head rivets. If this isn't the correct term, then it should be. Very tedious. I tried using a form tool on the heads but unless I went very slowly indeed it just twisted the head off.
It proved much quicker to swing the compound slide over and turn the angle.
These are what hold the hull of the vehicle together and there are loads required. I cant bring myself to actually count how many hundred I need yet. Apparently my casting was sent yesterday so hopefully should arrive soon. Its been pointed out (correctly) that I have the tracks fitted the wrong way round. I really must rectify that soon.
|
|
mbrown
Elder Statesman
Posts: 1,720
|
Post by mbrown on Dec 20, 2023 22:26:46 GMT
Yours is the most accurate way of modifying rivet heads - but when I wanted some pan-headed ones I made a dolly with the dimple the shape I wanted and found that the process of closing the rivet gave me the right shape.
However, it looks as if you have too much metal in the existing heads to achieve the pointed shape just with a dolly, so I hope turning them all isn't too mibd-numbing!
Malcolm
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 22, 2023 16:54:18 GMT
I had just got back from a pub lunch and a pint of San Miguel today when there was a ring on the doorbell and a nice man presented me with this. When I was making the pattern I realised that I was being a bit naive to expect a cast finish to produce a scale finish. Also, I was concerned that the casting might come out a bit out of round (it didnt). With this in mind I made it slightly larger to allow for machining to final size. When I made the pattern I included a recess on the inside for the lathe chuck to hold on to.
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 22, 2023 17:00:20 GMT
Unfortunately a blow hole appeared in the casting during turning. This was easily remedied. I gave it a bit of a tickle with my dremel grinder to make the iron shiney. Then tinned the area with solder paint and filled it with plumbers solder. All without removing it from the lathe So I was able to clean it up very easily afterwards.
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 22, 2023 17:06:06 GMT
Well if it is anything in the region of the price I got for miken it is quite reasonable. It was very reasonable. Cheaper than the original quote they gave me (20% cheaper). Thanks Graydon Castings. And Jason for his help.
|
|
jasonb
Elder Statesman
Posts: 1,209
|
Post by jasonb on Dec 22, 2023 18:27:14 GMT
Looks like it turned out well, the lower price may have been due to your casting being a bit lighter than the weight I calculated from my 3D model, nice of them to pass the saving on.
|
|
JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,909
|
Post by JonL on Dec 22, 2023 19:09:38 GMT
This is fantastic! Following with extreme interest. My son has expressed an urge to do something like this in the past.
I was tempted with a Cromwell... lots of straight lines... or a Covananter...
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 22, 2023 21:31:38 GMT
This is fantastic! Following with extreme interest. My son has expressed an urge to do something like this in the past. I was tempted with a Cromwell... lots of straight lines... or a Covananter... Aah, the Covananter. I really like the look of the Covavnanter. Designed and built by that famous tank builder, the London Midland and Scotish Railway. Very nice looking but thought by many to be the worst tank built by Britain during WW2. That is quite an achievement because there was a lot of competition! So bad that during the desperate early days of the war, although 1770 were built, they were so unreliable that none were deemed fit for active service. The problem with building large scale model (all metal) tanks is always the tracks. When you start looking closely at track links it's always really hard to find something that you can fabricate yourself that's going to end up looking right.
|
|
JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,909
|
Post by JonL on Dec 23, 2023 14:01:43 GMT
Agreed. It was the track links that put me off. I almost crumbled and purchased an Armourtech kit but resisted.
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 31, 2023 22:03:36 GMT
Ive been working on the hull. Its about the size of a large 5" gauge locomotive tender. A lot of the plates come together at unusual angles which make the job quite interesting. My method of construction is to build and assemble it with screws. I drill and tap for M3 leaving a bit of overlap on the corner joints. I then dismantled it and tinned all the joints with solder paint. Reassemble using stainless steel screws. Then warm up and feed in a bit of thin electrical solder to the joints. Any unwanted gaps are caulked with a bit of plumbers solder. Remove the screws. The solder doesn't stick to the s/s screws. Then clean up all the plates and file/sand off any lumps of solder. File off and oil stone any overlaps on the plates. Then, start riveting. I found it best to refit a line of screws to the joint I wanted to rivet, then remove one or two screws at a time and replace with a rivet. The inside isn't very elegant looking. the rivets are just bashed over into a countersink. This brings me to my to my next point. This project has received a lot of interest and kind remarks. But no one has actually asked me what Is going inside the tank. Originally i thought it would be interesting to make a static model with a detailed non working interior. However i have realised that this isn't going to impress my 2 grandsons (3&5) for very long. So the plan is to fit electric motors and radio control.
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Dec 31, 2023 22:07:39 GMT
I find that usually, one good bash per rivet with the club hammer usually does the job.
|
|
|
Post by chris vine on Jan 1, 2024 0:13:22 GMT
There was a gentleman (Australian?) at an me show a few years ago with a tank with a model v12 engine inside…. Chris
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Jan 1, 2024 21:00:32 GMT
There was a gentleman (Australian?) at an me show a few years ago with a tank with a model v12 engine inside…. Chris h Impressive. That must have been a challenge. I would guess a miniature engine like that would be quite high revving? Would take some gearing down I think.
|
|
|
Post by chris vine on Jan 1, 2024 22:01:39 GMT
When I saw it it was running only 10 cylinders, so he had problems. However, it seemed fairly slow running to me. I guess with that many cylinders it isn't so lumpy as most model engines.
Quite a piece of work! Chris.
|
|
jasonb
Elder Statesman
Posts: 1,209
|
Post by jasonb on Jan 2, 2024 7:22:47 GMT
Only problem with making a V12 for it is that your Grandson may be 22yrs old before it's finished. An the shelf V8 from China may be an option but electric is probably more practical. This is the one Chris mentions, I think it was Sandown where I saw it. youtu.be/e9d6jrX3WX0?si=N5mrk07SD8UnBnYo
|
|
miken
Part of the e-furniture
Posts: 480
|
Post by miken on Jan 2, 2024 12:55:34 GMT
That is an extremely impressive piece of work. I shall stick with something a little simpler.
Btw, the original Renault tank was powered buy a 4.5 ltr straight 4 cylinder sidevalve petrol engine producing 42 bhp.
|
|