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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: Sharpening Files
13/05/2020 12:11:41

On a related subject, cleaning files rather than sharpening them. I have a set of needle files marked 'Diamond Brand Made in the Peoples Republic of China'. They are about 40 years old and have seen a lot of abuse over the years. Most of them are still good but one or two have become badly clogged with bits of soft metal such as aluminium, solder, diecast zinc and other assorted materials used in a variety of model railway and household objects. I would really like to clean them up a bit but don't want to damage whatever residual cutting edge they still have. Some have recovered through being used for filing bits of steel which has cleaned out the grooves nicely, but others have so far resisted that treatment. Any suggestions for how I might go about this which does not involve scraping out individual grooves using wedges of brass under a magnifying glass? Thanks

Thread: Cabinets
11/05/2020 08:28:28

Or put substantial rails (eg unistrut or similar) running along under the feet of the lathe bed to transfer the weight to the load bearing locations? Might interfere with sweeping out swarf and/or flow of coolant to drain points but likely that could be overcome with a little thought. Bonus is raising the height of the lathe a little as I found my Sieg C6 with supplied stand about 75-100mm too low for comfort. Put the whole stand on 75 SHS rails with rubber pads under to protect the floor as well as stop the machine from wandering.

Thread: Dead centre vs. live centre
02/05/2020 11:56:07

Further to the response from Norman (NGH) you will find when working close to the tailstock that it is easy to run your tool or toolholder into a rotating centre and either blunt your tool or turn a groove in the rotating part of the centre. I've done both. With a dead centre there's less potential for damage.

Thread: Cutting a slot in a turned piece
28/04/2020 00:04:49

I've not done anything like this myself, but I'm wondering if it would be sensible to start with bar stock in the lathe, drill out the centre, turn the outside, then transfer to the milling machine to cut the slot before returning to the lathe for parting off? That way you have the ridigity and chucking ease of the bar stock while turning, and something to clamp onto while cutting the slot. The only tricky part is parting off an interrupted cut.

Thread: Lions and Human conflict - What to do during Lockdown
20/04/2020 13:32:14

Fascinating, it must be quite a thrill working closely with such majestic animals, even when they are anaesthetized. Lots of work in those trackers too, must take some time to assemble even with the aid of jigs and templates. Well done.

Thread: F1 Simulation
20/04/2020 02:43:41

The V8 Supercars series in Australia has also developed an E-series simulation involving all the main drivers which looks pretty good: **LINK** They even managed to get Max Verstappen to join in.

Thread: Airbrush
19/04/2020 13:04:49

Before safety become an issue we used to use an old car tyre as a make-shift receiver. It would take up to 40PSI quite easily and provided a good buffer to prevent the compressor cutting in and out too often.

Thread: Aircraft Guidance Lights, Or?
17/04/2020 10:50:37

Could you perhaps mount your binoculars on a tripod, aimed at and focussed on the night-time lights, and then leave them in that position until a clear day and see what is revealed?

Thread: Metric taps and dies - and pitches
16/04/2020 12:14:25

As far as I can work out, when metric threads are nominated simply by (say) M10 with no additional information, it refers to coarse thread pitch which in this case is 1.5mm. If a fine pitch thread is called for then it is nominated by M10 - 1.25 meaning a thread pitch of 1.25mm. In general, most of the commercially available metric screw threads less than M8 are coarse. The reason for having differing pitches is hard to identify, but the Nord-Lock website has a useful summary here: **LINK** which might help. I suspect that in the smaller sizes, the tolerances required for fine thread cannot be easily maintained in manufacture so the coarse thread prevails. I'm happy to be enlightened by anyone with more accurate information.

Thread: What am i going to make with this scrap
10/04/2020 09:53:37

Cup-holder to bolt to the side of the lathe or milling machine??

Thread: Australian Crayfish?
07/04/2020 13:17:27

As an Aussie I can confirm that lobster/crayfish is expensive here, usually around the figures you mention at public fish outlets. Those prices are for whole cooked lobster, but if you buy prepared lobster tails the price can be even higher. I don't know what duration the season is. One of the reasons for the high local price is that the majority of our premium shellfish such as lobsters/crayfish are exported, fetching high prices because of their quality, and the domestic market therefore has to follow. Apparently the current Covid 19 restrictions have caused prices for some of these delicacies to drop by up to 15% due to reduced demand, as most restaurants are closed and some overseas trade has slowed as well.

Thread: I once built a go cart
06/04/2020 12:46:47

When I was a kid we built 'soap-boxes' but we called them billy-carts, usually made from scrap bits of timber and recycled pram or stroller wheels. We had some good hills around home, little car traffic, so plenty of action. Very few spills, the fear factor kept us safe (not fear of being hurt, fear of facing mum with torn clothes from coming off at speed!) As our skills and budgets improved some ended up with rear suspension (trailing arms using gate hinges, old valve springs from Dad's Morris 6), brakes (a pivoted lever bearing against the back wheel), and 8-wheeler that would seat 3 kids, and one of my mates even had a steering wheel set-up using recycled vee-belt pulleys from a washing machine. That was a trick billy-cart as he put the ropes on the wrong way so to turn right you had to steer left and vice-versa. Fun times.

Thread: Wow, what a battery
04/04/2020 11:58:36

My only question is, what date was the ad posted. If 1 April then I guess the obvious answer is..........

Thread: Some help needed with my build
04/04/2020 11:54:42

I know this might be frowned on, but the linkages sold for use in R/C aircraft would seem have the right size range available and appear to be relatively slop-free, reliable, and readily adjustable. Only question is whether they have the strength and durability for this application?

Thread: Bottom of the beginners heap
02/04/2020 12:13:32

Looking forward to the photos, I have an Ideal dating from 1929, don't know what year yours would be?

Tony at would be a good source of info on what accessories may have been made to suit later models. He'd probably also be interested in info about yours as they are not a common brand. You also might be able to identify the other lathe from the info on his website, but be prepared to trawl through hundreds of photos!! Geoff P.

Thread: How are your clubs responding to Coronavirus
17/03/2020 11:28:35

Grandchester Model Live Steamers (Queensland Australia) have suspended public running days but will continue with private club days, working bees, committee meetings etc in the meantime.

Thread: Bending and shear force confusion....
09/03/2020 02:10:27

If I am understanding this correctly, the original has a full length bar of the same diameter as the pin in Scenario B, but the bar bends where it enters the boss. If that is the case then replacement of the bar with the pin and separate handles will achieve greater pressure, provided that the handles have greater resistance to bending than the original bar. In the original, if the bar is a loose fit in the boss, the bar is subject to both bending and shear, with the resistance to bending being much less than the shear strength. If the pin in Scenario B is a press fit, then it will only be subject to shear stress. Theoretically you will get greater pressure in the press, until you either exceed the shear strength of the pin or the bending strength of the separate handles, or the tensile strength of the boss where the handles are pressed into it.

As others have said, be careful that your improved design in one part does not overtax other parts not designed for the additional forces you are now able to generate.

Thread: Wood or Charcoal
07/03/2020 11:23:18

The steam loco owners at our club generally use timber pieces doused in Kerosene (Parrafin) for starting their fires. Never have any problem with tarry deposits as it is usually well-dried hardwood from the local sawmill. In fact there is one driver who fires his 7-1/4" gauge loco using nothing but wood. He uses offcuts of recycled hardwood from making timber sleepers for his home track. After a couple of hours hauling passengers on a public running day he would be lucky to fill a teacup with ash from the smokebox and there was very little in the firebox either.

Other threads on this forum have discussed the best timber for use in fireplaces and wood-burning stoves to reduce ash and avoid tar buildup in flues, seems to me the same principles would apply to firing model boilers.

Thread: Powder coating
04/03/2020 11:28:54

Properly applied powder coating is very durable and does not usually flake off unless the substrate has not been properly prepared. There are umpteen thousands of powder-coated whitegoods in houses all over the world which in general seem to last quite well, although not exposed to the elements. There are also many thousands of powder-coated bicycle frames in use all over the world that are often exposed to harsh conditions and seem to last pretty well. I have at times refurbished bicycles and I can confirm that removing properly applied powder coating is a lot harder than removing paint.

Thread: Paint prep
02/03/2020 08:58:09

More years ago than I care to remember I overhauled a side-valve Ford Prefect engine. Painted the whole block and head (both cast iron) with 'Engine Enamel' which was a supposedly temperature-resistant paint. Went on neat, no primer or undercoat required. I had already cleaned the block using kerosene and a stiff brush followed by soapy water. Paint was still in good condition when I foolishly sold the car 20 years later. Perhaps the vintage car and motorcyle owners in this forum could suggest a modern alternative?

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