Member postings for Bill Davies 2

What works for me is to use drills one third the size of the previous one, obviously depending on the torque available. As the original post said, basically the web is the problem, so the less 'scraped' or pushed out the way by the web the better. I frequenlty use 3mm or 1/8 as the first drill, but it does depend on the machine. About 1.5mm on my minilathe.

Bill

I bought a GH universal mill plus various bits of tooling from Warco April last year. I had spent about a year, on and off, comparing models and brands, and building up a spreadsheet to compare features. I trawled websites comparing the quality of service people had received, and the arguments for and against old European/modern Chinese machines.

Having worked in several FE colleges, I knew that many had ‘good old’ machines, but also how poor the condition was of many of them, after 40 or so years in the hands of beginners. At my last college, I was responsible for replacing old Colchester lathes with new ones. The old ones were becoming unreliable and having multiple faults, like an old car, and getting beyond repair. I twice visited Warco at Chiddingfold from South Wales, looking at second-hand machines, and came close to purchasing something each time.

In the end I bought new, and I’m happy with my mill. The electrics (1ph) contains nice contactors made by Siemens with low voltage care of a chinese transformer, all wires numbered. The paintwork is adequate, but chips easily on edges, Warco green, not my preferred colour, but pretty much what I was surrounded with when I worked in industry. The tee slots came filled with a thick brittle black paint (over swarf) that prevented tee nuts sliding until it was scraped away. Perhaps it was to protect the slots during shipping? No heavy anti-rust treatment (cosmoline to US), so it was easy to clean up, no corrosion visible.

Several items, including stand, were not available at the time, but were delivered on back orders. Warco updated me as required, by email and phone. Roger Warren was helpful. I bought a vice from Axminster, as Warco didn’t have the size I wanted at the time. Once run in, it’s no noisier in a standard garage than I would expect, especially in lower speeds. I have cut cast iron, mild steel and 1/4” thick gauge plate, and lightly skimmed a case hardened angle plate, all with HSS end mills.

I hope this helps others, who may be unsure (as I was) about an expensive decision.

Bill

If it's bright mild steel, skim each face equally, possibly in a couple of passes, to get rid of the stresses in the outside 'skin'. It will still move a bit, so you might still, as vintageengineer says, need to straighten, but it would be much less.

I had a stab at making drilling vice many years ago, cutting out the central section on a horizontal mill without skimming the outside, and was amazed how far the work 'moved' when I removed from the vice.

Bill

I agree with Neil; the silicon cable is more flexible (and resistant to burns from the iron). The PVC cable is a bit stiff if you are working in a cool workshop. Worth the small difference in price. Also, +1 for using tip cleaner, but excessive use seems to eat the bit. Just use it to remove crud.

I havent tried the 'brass swarf' tip cleaner which appears to mechanically clean, rather than chemically. The moist sponge works well, but again, excessive use causes thermal shock which seems to degrade the bit. I also find it better to leave excess solder on the tip when I finish a session.

Bill

Years ago, I helped a friend rebuild an AC Greyhound. When refilled and run with motor oil, the oil went silvery, which we put under a microscope,and could see the fine particles. Contacting various manufacturers, Morris of Shrewsbury suggested a 'straight' oil without additives, and everything was fine after that. With hindsight, I could imagine that some part was bedding in, but there was no subsequent evidence of wear.

Bill

As Martin states in the second post, the standard cutters (hob and gear shaper) are easier to sharpen without complicated setups, at least for shaper cutters for producing spur gears. They are sharpened on their front faces, and can be ground back until the teeth are quite thin and at risk of breaking, without affecting the tooth shape very much. They are therefore long-lasting, which the teeth on an end mill would not be.

Hobs and gear shaper cutters are both produced by essentially straight sided grinding wheels. A screwcutting motion of a form tool or grinding wheel produces hobs (plus a cam action in the cross slide to provide backing off), and by involute generating movements in the case of gear shaper cutters.

Furthermore, the specialised machines already exist in the market and are suitable for quantity production. Both types of gear cutting machine can be set up to produce helical gears, albeit with modified tooth form for hobs and also matching helix angle for gear shaper cutters.

One-offs can be produced on a horizontal mill with an involute form cutter, using one of the typical set of eight form relieved cutters to cover the range of numbers of teeth, although only spur gears would have the correct tooth form and thickness to mesh with existing gears of matching pitch.

Bill

A brief browsing; I'm sure there are many sites, but this gives some interesting info:

**LINK**

Bill

I have found that neodymium magnets, once the surface plating is cracked or damaged, tend to break down fairly quickly, that is, over months. They just seem to crumble, even if not handled. As Thor says above, the material is reactive. I suppose that whatever they are sintered or bound with is minimised for the sake of the magnetic properties. I have considered reinforcing with araldite to get the shape I want, but to make best use of the magnetism requires the attracted part is very close to the magnet.

Bill

Chris, it looks like a jacot tool, used to polish watch pivots. It seems slighly different to the normal form which is more symmetrical. Google to find many examples.

Bill

Sorry, I didn't embed the links:

Drving dogs: **LINK**

Mandrel with flats: **LINK**

Bill

Roger, the flats are for driving dogs, and you might find size and perhaps other info stamped or etched on the flat surface. It is possible, with care, to grind oppposite surfaces by turning the mandrel and work end-for-end, to avoid any changes to the work's position with regard to its centre line. Given the very slight taper, for precision work, the workpiece could cant very slightly, and opposite faces would not be parallel. Having said that, when I was "bossing and facing" the ends and registers of cutters, I pressed the mandrel out, turned the work around, and pressed the mandrel in again.

I have a vague memory of one end sometimes having a ring (or am I thinking plug gauges), but certainly one end was often shorter than the other.

The [driving plates/dogs, catch plates] I used were lighter than the lathe types, and with arms off both sides, similar to the third picture here:

https://katalog.mav.cz/categories.php?rozbal=3443

This reduces any imbalance in the work, which might otherwise show up in the roundness/concentricity of the work.

Here is an example with flats on both ends:

http://www.ebay.com/itm/TTC-Lathe-And-OD-Grinder-Mandrel-Diameter-1-3-4-Overall-Length-10-/231948753418?hash=item3601391a0a:g:A3oAAOSwcvdXPHvJ

My Machinery Handbook (17th Ed., 1964) mentions mandrels in the index, but calls them arbo[u]rs in the text, and recommends 0.006" per foot for turning. Each end is shown the same length, and it doen't mention their use for grinding.

My Workshop Technology Pt (Chapman, 1968) shows the steps in grinding a headed bush, by grinding the bore, then, on a mandril, grinding the ODs and faces on one side, reversing mandrel and work, then facing the other end.

Bill

I'm glad you identified them, Roger.

The ones I used were for holding high speed steel gear-cutting hobs, and hardened; some were hard chrome plated.

These mandrels had a taper of only a few tenths of thous, as the diameter of the bores were within close tolerance, being ground and honed.

If you find tapers of several thou or so, then I would sugest they are for 'soft' work; turning or milling, but remember these are friction fits, so the cutting forces need to go towards the larger end.

We used a hand powered mandrel press, but not much force was required to press them in, but as I said previously, this was for grinding operations.

Bill

Mandrels? Do they have centre holes each end, possibly slightly counterbored for a shallow recess? Are they slightly smaller diameter at one end, and possibly hardened?

I used mandrels years ago to grind aspects of cutting tools located accurately located off the bore. For example, grinding concentric registers for truing the cutters up before use, grinding the radial faces of the cutting edges with a thin grinding wheel.

See:

**LINK**

Bill

A reference to the tool in this video: Play the "Tool Knowledge Challenge"

**LINK**

Bill

Doesn't the DIN 9000 in Clive's post refer to the quality procedures that the firm is prepared to be audited against? Also known as ISO 9000?

Brian,

I have sent you an email. I have an old treadle lathe, probably a Britannia 14, which had its treadle gear removed long ago, and has a small motor driving it. It does not have a screwcutting gearbox. I think it was made about the turn of the century.

It is virtually identical to: **LINK**

And it evens sounds the same!

Regards,

Bill

First post.

If you double the diameter, you halve the speed. The speed of the work moving past the tool remains the same.

The torque has doubled (half the speed) but so has the radius, so the force acting on the tool is the same.

Thus, the same depth of cut and feedrate will work at any diameter. This is true for geared heads with a fixed speed motor, but I would think not for variable speed drives.

Bill