Member postings for Andrew Johnston

Well I did try it.

I don't have any 638 so I used 648, a similar high temperature Loctite. The pin was a short length of 5/8" low carbon steel and the block a scrap piece with a 16mm hole drilled in it.:

The hole measured 15.96mm and the shaft 15.86mm, so a gap of 0.05mm. Before assembly the parts were abraded with emery cloth and cleaned with acetone. Assembly was as per the datasheet with a twisting action to ensure complete coverage. After assembly the parts were left in the airing cupboard for 72 hours to cure.

After curing, with the body in the vice and a Mole wrench on the pin, nothing moved no matter how hard I pulled on the wrench. I then put the parts in the electric furnace set at 300°C. After an hour or so I extracted the parts and put the body back in the vice and the Mole wrench on the pin. The pin moved under the weight of the wrench and came straight out . The Loctite had been converted to a light brown powder which brushed off easily leaving the original surface:

Pretty much what one would expect from reading the datasheet with a bit of engineering interpretation. Datasheets are a marketing tool to help sell the product, so they're hardly likely to downplay the product while not telling actual lies.

Any questions?

Andrew

Good grief, you need to be poised over the keyboard ready to post these days, or you get gazumped!

The Skyvan morphed into stretched versions, the Shorts 330 and 360. The wing always looked far too small, especially for an aircraft that could operate from relatively short runways.

Andrew

Edited By Andrew Johnston on 18/11/2019 16:49:03

I've just looked at my screws. The top screw is about 5/32" long and is longer than the lower screw by about 15 thou. However i don't think these screws are the original. The upper hole is about 7/16" deep while the lower hole is 3/16" deep. The lower screw has been cut down from a longer screw, while the upper screw looks unaltered. My head is a 2JB.

The screws could definitely be different lengths, in contradiction to my manual. But it wouldn't be the first time the manual has been wrong.

Andrew

If you scroll down the page on this link:

Quill Assembly

The screws are indeed different lengths, although the thread looks the same. I'm surprised the bean counters didn't smack the designer round the head for using different length screws. It doesn't alter the fact that in my original Bridgeport manual only one part number for the screw is shown. Once the weekend is out of the way I'll take the screws out of my scale and have a look.

Andrew

Welcome to the forum!

I was in Northumberland last week, gliding at Milfield near Wooler. Well, actually watching it rain instead of flying. I'm a regular visitor to the area.

Andrew

I'd be very surprised if they were different threads. In my manual they're not listed as different screws. It's not uncommon for a thread to be slightly damaged or full of gunk such that a screw appears not to go in. I'd carefully run a 6-32 tap (ideally plug) into the hole to clean the thread.

Andrew

Yes, what's the question?

Andrew

I am in the process of changing the flourescent tubes in my workshop to LED tubes. I am also changing the battens to LED specific ones. I decided to change as the original tubes were becoming increasingly unreliable and one choke was getting too hot to touch. They're 20 years old, so time to change. I chose high colour temperature LED tubes, 6500K. Impressions so far are good; the tubes start instantaneously and give a bright, almost clinical, light. I should save between a half and two-thirds the power of the flourescents.

Having had LED downlights fitted in my recent main bathroom and kitchen refurbs, and fitted new wall lights with LED bulbs in the lounge, I am now changing all my house lighting to LED. For the house I chose a lower colour temperature, 4000K.

I expect there to be a significant power saving as well as better, brighter, light.

Andrew

The way I read the original post the 44 ohms was between any two terminals with the motor in star. Given that the star point is buried it presumably doesn't appear at a terminal. Therefore the 44 ohms is measured across two windings in series. So each winding should be 22 ohms.

Andrew

Forget the stock and remove the chuck. If the lathe still wobbles then there is a problem. If not then the issue is with the chuck/stock. Also check to see if the problem gets worse with increasing spindle speed.

Personally I'd bolt the lathe down. Even new it won't be perfectly balanced and a small imbalance can be magnified if the lathe is free to move.

Andrew

Sometimes you just need a larger mill:

And VFDs are great but sometimes you need power at low spindle speeds to drive a 1" countersink in steel:

Can't remember where I got the countersink, but I think it was in a box of bits 'n' pieces I bought from a member of my gliding club as they were too big for his machine tools.

The steel plate is 600x500x15 and is one of the very few times when unknown material I've been offered has turned out to be useful.

Andrew

Where did that come from? Looking at the datasheet for 638 it is down to about 35% of initial strength at 200°C. Extrapolating the curve (always a dangerous thing to do) it crosses the zero axis at about 250°C. I wouldn't trust 638 at 300°C.

Andrew

I'd agree; "rules" in books, and on forums, are for guidance not blind obeyance.

While boring bars are not generally defined as thru hole or blind they are defined by the features they will machine. Tthere are many that will not bore and face a blind hole. Search for SSKCR/L, SDZCR/L or STWPR/L for instance.

This is what I meant by microboring tools:

Microbore Tools

Andrew

Had it once yesterday, but not today. Seen it before; I just ignore it.

Andrew

I've milled a lot of hot rolled steel and never had a problem with distortion. Although there was a thread recently where someone had experienced distortion after milling hot rolled steel. If I recall it was quite a thin section. I'll see what happens when I mill the small hot rolled section to make the beading for my traction engine tender.

Cold drawn is a different animal, and not just steel. Cold drawn brass will distort as well. If I need to mill cold drawn steel I normally heat it to 800°C and let it soak for 30 minutes or so per inch of thickness. I then let it cool slowly. Of course I have the luxury of an electric furnace so soaking and slow cooling are fairly simple. I've never had a distortion problem after heat treatment.

Andrew

The insert shape used is determined to some extent by the reach and whether the hole is blind or thru. It's a moot point anyway; I doubt you'll find a common boring bar and insert combination that will bore 8mm out to 10mm. Of course there are specialised microbore insert tools available, but you'll need to sit down before looking at prices. A small HSS boring bar will be just fine.

Andrew

Depends upon the exact material spec. If it's EN24T then it's hardened and tempered so has already been stress relieved to some extent.

Andrew

Old school manual mills are massive, but the material is essentially in the right place. Look at an industrial vertical mill and the column is much deeper than wide. And the column depth narrows towards the top. In simple terms the column is a beam in bending and unsupported at one end. The equations for bending and stress have long been available so basic deflections and stresses can be worked out with pen and paper.

The column on the WM18 is much narrower fore and aft than the width, So it is poor at resisting fore and aft bending due to the weight of the head and vertical forces resulting from, say, drilling.

Yer pays yer money and takes yer choice!

Andrew

I've used all the features and all the accessories I have, with the exception of the Quillmaster. As I've picked up extra tooling some features get used less. Now that I have a large tilting table it's quicker to use same rather than tilt the head. Likewise if I need to drill parallel to the table it's easier to fit the right-angle attachment than swivel the head. I have run out of X, Y and Z travel on the Bridgeport, but there are ways around the problems.

I've got a lot of tooling squirrelled away for my machine tools. Makes sense; if you don't have the item you can't use it. But if you do, it can make a job much easier, even if only once in a blue moon.

Andrew

No, but as the quality of the picture has gone up, the quality of the programmes has gone down. Sure doesn't run into the Shannon-Hartley law limitations. On the plus side it means I spend more time in the workshop rather than on the couch.

As SoD hints, of the low carbon steels En1A turns very well and the leaded version, EN1APb is even better. However EN3B has a propensity to tear and needs some experimentation to get a good finish. I use a lot of EN3B as most hot rolled steel is essentially EN3B, and is cheaper than cold drawn.

I also find that EN1A rusts easily, often overnight, whereas EN3B is much less prone, even in a damp environment, like a kitchen.

Andrew