Member postings for Brian G

Both of the photos show grippers fitting outside the screw, but there is another way. My father used to have a flat blade screwdriver (I wish I had a photo, or better still the screwdriver) that gripped inside the slot.

The tip was divided into three parts. The two outer sections were integral with the tubular shaft, and formed a fork, similar to a security screwdriver, whilst the centre section had a straight shaft and parallel tip like an electrician's screwdriver, passing straight down the centre of the shaft. This was spring loaded to rotate about 60 degrees relative to the rest of the blade. To fit it to the screw, you simply turned a knob to align it with the rest of the blade, and when released it gripped inside the slot.

Brian

No need to run a chain over sprockets at each end, as if it is fixed at both ends of the bed and engages with a sprocket on the saddle, it will behave like a rack and pinion (That is basically how a chain ferry works.) Two idlers could be used to keep the chain horizontal and run it around a sprocket on the apron in an omega shape, or if the chain could be mounted high one end and low the other a single idler could be used, as in the Brooks tool and cutter grinder described in MEW 16.

I have a replacement tailstock on my Unimat SL that has an integrated ER11 collet holder and a Unimat 3 14x1 thread for the collet nut. Perhaps it might be worth considering doing the something similar for your new spindle, but making a collet closer with a 1/2" BSW thread? That way you could hold 0.5 to 7mm (or 8mm with oversize collets) within the spindle and still use your threaded tooling.

Brian

Don't be put off by machining silver. I used to operate a quantometer that used a silver electrode which needed to be skimmed clean each time, and have never met a metal that was easier to turn. No need for any lubricant, just a sharp tool and a steady feed to produce a literal mirror finish. I would expect it to take a thread well, although it would be easy to strip.

Brian

Fortunately somebody does

http://www.hatads.org.uk/ads/ghostsigns.aspx

As a child I was always confused by road signs that said "Unsuitable for heavy locomotives", not realising that the traction engines I saw at rallies were legally classed as road locomotives.

Brian

Edited By Brian G on 18/11/2015 10:22:52

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Edited By Neil Wyatt on 18/11/2015 11:48:13

Raboesch make styrene tubes all the way up to 18mm i.d. / 20mm o.d. John. In my experience they are pretty accurate on dimensions, but you will probably only find the larger diameters in 1m lengths.

Not that easy to find, try your local model boat shop as they also make propellers. If not you could mail order from Cornwall Model Boats, but postage might be expensive in proportion to the cost of the parts due to the length.

Brian

I use a cutting plotter (as used for vinyl signs) to cut styrene sheet accurately and use thin cutting mats like this **LINK** to support the sheets. They are not completely self-healing, but take a lot of damage before they need replacing. When new they hold the cut parts in place perfectly, but after while they lose their tackiness and need to be refreshed using repositionable spray mount.

Alternately you could just try the repositionable spray mount on your existing mat. It is a bit of a so-and-so to clean off, but can be removed with soap and water.

Dezincification was what worried me, although in this case I wasn't sure which metal would dissolve first. Fortunately it looks like a lucky escape as my son just heard back from our friend that the parts involved were all bronze and appear OK.

Thanks

Brian

A friend put some boiler fittings in diluted Kilrock (formic acid) overnight to remove limescale and remembered them a week later. Unsurprisingly the parts are now bright pink, but we wondered if any damage may have taken place deeper into the metal that could affect their performance?

Thanks for any advice

Brian

You could use a micrometer or calliper to check that the length of all four faces is the same (near the corners, not from the centre of the face) and then measure the diagonals. If these are the same as well, the bar is square. The beauty of this method is that you don't need any kind of calibrated equipment, or to trust that a square is truly square, even a friction-joint calliper is enough to check if two dimensions are the same.

I will confess to an unfair bias against squares due to the sheer number of complaints forwarded to me where customers, mostly "engineers", tried setting out a greenhouse base using a 6" square rather than simply following the instructions and measuring the diagonals. Even a piece of string would be more accurate than a square on a 12 x 8 greenhouse.

Brian

Off-topic for the drill, but in Chatham Dockyard a Fearnaught was similar to (or identical to) a donkey jacket, although my father's for some reason was white.

Back on topic, I once had to source replacement chrome leather belting for an elderly machine (used as a feed conveyor as it picks up gently and didn't damage the finish on powder coated steel), but I only know British suppliers. If there are no pulleys bearing on the reverse of the belt you might extend the life with a fabric backed belt. A quick web search has turned up an Australian company, but not having dealt with them I cannot personally recommend them. **LINK**

Brian

Electro-brassing is very common in (or rather on) cheap hardware such as door bolts, hooks and rusty brass screws. 30 Years ago I started a new job as production planner in a door factory and my first task was to find a supplier for brass self-tapping screws! Fortunately I knew a local plater pretty well and was able to get some stainless screws to him the next morning. It took me three months of arguments with the design office to get the drawing corrected though.

Brian