Member postings for Gary Wooding

Wallace,

will you give permission for it to be published in my club's newsletter?

Gary

I've done lots of silver soldering and yes, its basically fairly straightforward. But I strongly advise you to get lots of experience before tackling a boiler.

Boilers are large lumps of copper which require correspondingly large amounts of heat for a successful job. Somebody at your club must have done one at some time, so talk to them. Have a look at the equipment they used and try it out. Start small and progress upwards; copper and silver solder are expensive these days and, despite it being basically simple, the sheer quantity of heat required can be very intimidating. Its normal practise to use two torches: a large one for getting the whole thing nearly up to temperature, and a small one for locally heating the joints to melt the solder.

I'm sure you can do it, but gain some experience on simpler things first.

Coincidentally I have the following for **sale**

Humble pie tastes horrible - arghh.

I decided to try it out with a CAD program. The following *LINK* illustrates that randomly spaced pinions cannot be fitted between two racks.

Gary

What you say is true only if it's a requirement that the pinions have the same orientation, but I don't see why that is a requirement. Equally spaced, yes, but why same orientation? All gears are based on rolling cylinders or cones, the teeth are simply to guarantee no slipping. Where does the equal orientation come in? No matter what the orientation of the pinions happen to be, the second gear is bound to mate properly.

The point I was trying to make with the rack is that the two racks will mate with the pinions no matter how they are spaced. Random or equi-spacing has no effect on the mating.

Gary

I found the MEW article "Design and CNC Machining of Straight Tooth Bevel Gears" very interesting, but one statement defeated me.

On page 14 the author states...

"This particular differential has 3 pinions equi-spaced around the gear. It is important that the number of teeth on the gear is divisible by three, with no remainder. Otherwise the three pinions will not sit equally spaced around the gear, each in the same orientation, and will not therefore mate with the second gear wheel."

I agree that the number of gear teeth has to be an integral multiple of three in order for the pinions to have the same orientation. But why do they need to have the same orientation? The second gear will mate whatever the orientation of the pinions.

If you image straightening the gears to make two racks, then it is clear that they will mate with any number of equal sized pinions, whatever their spacing. Or have I missed something?

Gary

VFDs are not torque multipliers. They don't work like gears, where halving the speed doubles the torque. In essence, a VFD driven motor will give constant torque at speeds at and below its rated speed (ie. its speed at 50hz in UK), and constant power at speeds above. This means that power is proportional to speed up to the rated speed, and then remains constant up to maximum speed.

There are VFDs that purport to give increased torque at slow speeds, but I don't think its significant (can anybody supply more information?)

I've fitted cheap VFDs (around £50-£70) to 3 mills, 3 lathes and a bench drill, all of them will work up to 120hz - that means that a 1425rpm motor will spin at 3420rpm.

I seldom change the gears or belts on my machines; I use the VFDs instead, but there are occasions when I need the extra torque that only gearing can provide.

Gary

The real problem with HSS bits for threading, is the grinding and shaping to the correct angles. Take a look at the article "Really Simple Threading Tools" in MEW issue 159, page 44. It describes simple holders for internal and external threading, together with a very simple and easy method of grinding correct angles with a normal grinding wheel.

Gary

No it doesn't. I've done two and they're going strong 6 years later.

Gary

Basically true, but errors can still occur.

A few years ago, I was a member of a small team who had to design and build a special wheelchair. One member, who was very experienced with Autocad, accepted the job of creating the drawings. We should have heeded the warning signals when the first drawings appeared with dimensions in 1/10000", but we continued until one day we got a drawing where two important parts simply wouldn't fit. A dimension was exactly 1" out, to 1/10000"!. He had committed the cardinal sin of modifying a part without updating the dimensions.

Gary

Edited By Gary Wooding on 06/04/2014 17:55:00

I've repaired a few unsolderable things in the past by sewing them with 0.5mm stainless steel wire.

I use super glue to hold the parts together, drill small holes to take the wire, then use the wire to stitch it together. After the wire is pulled tight I then smother it in super glue. It works pretty well - not pretty, but serviceable.

Gary

I've created a PDF of the section of the article that tells how I made the tilt nuts **HERE**

I hope this answers your query.

Gary

Edited By Gary Wooding on 05/04/2014 13:01:23

If anybody is interested, some years ago I constructed a conversion chart for members of my ME club. It's in the form of a 2-page PDF that can be downloaded from...

**LINK**

It has the decimal and metric values of all Imperial fractions in 1/64"s up to 1", and tapping drill sizes for the common threads.

The tapping drill sizes were calculated with a 65% engagement for diameters up to about 3/8" or 9.5mm, and 75% for larger.

You can print it any size you like - I keep laminated A6 double sided versions near my computer desk and in the workshop.

You might find this useful. There is also an Android version.
**LINK**

This explains it.

Gary

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Edited By Gary Wooding on 25/03/2014 07:56:48

Edited By Gary Wooding on 25/03/2014 07:57:57

Quite so, if you only went to the centre; but if you went right across the face, the DTI would register twice the error when you reached the other side.

Gary

There is no argument about the requirement for a lathe to face perfectly flat. The real question is, given that perfection can never really be obtained, is it best to deviate slightly by turning concave or convex? My vote is concave.

Gary

Thank you.

It seems to me that your problem is illustrated in diagram A below. Your DTI method will align the spindle with the column, as in B. Then, by normal the tramming method, you will tilt the column until the spindle is vertical, as in C.

Not knowing the mill, I don't know how you will tilt the column, but the method is sound.

Gary