Member postings for Chris Gunn

We used to make a simple form tool to finish vee pulleys, just a piece of gauge plate, grind it to match an existing pulley groove, relieve the cutting edges, and harden. take the big volume of metal out with your parting tool, plus a little at each side, then use the form tool to finish, no messing about, and all grooves will be the same, which is important.

Chris Gunn

Soft jaws are a real benefit, once you have a set you will not want to be without them. My tip is to recycle them when you have machined them down a fair bit. When they have about 1/2" thickness left, machine them flat, and then carefully mark out and drill and tap a couple of holes in the centre of the jaws. Then make up some mild steel blocks to match the section of the jaws, and drill and counterbore holes to match those in the jaws, make the clearance holes as small as possible. The counterbore needs to be as deep as possible, then secure the blocks to the jaws with cap head screws, and you have some new jaws, almost free. I drilled mine carefully using a DRO to position them, and I made many sets while I was at it. I have been using the same base jaws for about 30 years, changing the blocks when needed. I have to make a new batch of blocks soon, but the scroll teeth on the base seem as good as ever.

Chris Gunn

Falco, thanks for those links, started downloading to my Kindle already, isnt technology wonderful!!

Chris Gunn

Paul just be careful with some of the alternatives to proprietary cutting fluids and lubricants, lard and rapeseed oil and the like will go rancid in the chip tray, probably a lot quicker in Oz than they do here.

Chris Gunn

The Super 7 leadscrew nut is awhite metal casting, and could easily pick up swarf. If is is worn and the screw is OK, you can replace just the nut.

CG

I would reiterate what has been said above, you need a lot of air to grit blast continuously, we needed a big screw compressor to run our sand blaster, and we needed dust extraction to keep the dust out of the workshop, and still it was messy, it would be even worse in a home workshop. I think Chris J was trying to say if it costs £40 to sand blast a mower, why go to all to bother to get the sprayer, media etc, plus the cost of running your compressor non stop, (is the Jun air continously rated, by the way?), when £40 could get the job done, dust and hassle free. On the same tack, I have just had 2 front and 2 rear traction engine wheels in 6" scale sandblasted for £50 cash.

Chris G

Wolfie, my tip concerns drilling, try and drill the hole you need in one pass, do not try and put a small drill through, and then follow up with a bigger one, as the bigger drill will dive in, and jam up. If you can use an offset point drill as suggested, do so. If the job has a stepped bore, drill the big hole first, then drill the small one second, if the job allows. If you are drilling the job in a bench press later, clamp it in the vice, and clamp the vice, and be careful the drill does not snatch. Use new drills if you can, if you have a miller, drill the hole in that, and use the table raising screw to put the cut on, not the drill press lever feed which you can lock up. Sharp tools are a must.

Chris Gunn

Metalsmith can offer 4mm square brass tube, could you use this, once painted, no one will know.

Chris Gunn

If you have got one, why not use it. Not sure what the starting current would be, maybe you should check this, as far as starting in higher speeds is concerned, if it is cold, my Bantam takes time to get to high speeds, as the oil is cold, when running from the converter. Once it has warmed up, no problem at all. If I go out and it is very cold, I run it for a few minutes at low speed until the oil has warmed up, then switch to the high speed.

Chris Gunn

I was faced with a similar decision when the 3ph motor blew on my Bantam. I had run this for years with a single to 3ph converter made by Transwave. I looked at putting a new motor on it, so I could use an Inverter with variable speed and so on. If I went in that direction, I would need to do something to run the 3 ph coolant motor, as I use this a lot. When I costed it, just for the main motor, the new motor plus new inverter, plus controls, all from suppliers who advertise complete solutions, it was not cheap, and still did not give me anything for the coolant motor. In the end I got the old motor rewound, and continued with the 3ph converter, which enabled me to run the coolant pump as well, for a quarter of the cost of the new stuff. I know I do not have variable speed drive, but I can still use the gearbox, all carefully selected by the original designers, and I can use the coolant. If you have no motor to rewind and no converter either, the economics will be different for you. Inverters are not the only solution.

Chris Gunn

I know it is a little off topic, but the mention of whale oil reminded me that the company I used to work for, way back, designed and built machines for scraping the last scrap of whale oil out of the wooden barrels it was shipped in. When we had a clear out in the drawing office, I kept the general arrangement drawing of this machine, beautifully drawn in ink on silk. I thought it might come in handy one day.

Chris Gunn

If you are in Northants or Bedfordshire, or willing to travel to Rushden for testing, you could contact the Rushden Miniature Steam enthusiasts society, who exist mainly for boiler testing road locomotives, although the boiler testing weekends are over for this year. The club does have a social side as well, and members are happy to assist and advise, but was originaly formed so a group could get their boilers tested. The membership fee is much lower than a commercial inspector would charge. Anyone wanting contact detail please PM me.

Chris Gunn

Edited By Chris Gunn on 13/04/2012 11:04:39