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Member postings for John Olsen

Here is a list of all the postings John Olsen has made in our forums. Click on a thread name to jump to the thread.

Thread: Ammco 7 shaper
19/09/2020 07:39:59

Usually with shapers when you change direction you have to turn the handle in the new direction a little to take up the backlash. After that, the friction in the nut is enough to stop the screw coming back. If it is not, then adding a little more friction to the screw would be the way to go. You may be able to do this by adjusting the end float. Another ratchet would be complicated and would also need reversing when you reverse the drive, which is why they didn't do it.


Thread: Are you too getting wound up?
19/09/2020 01:11:21

It can also pay to put a piece of paper between one of the jaws and the job, it will give a much better grip


Thread: close account
18/09/2020 06:02:30

So presumably if the same person had written a letter to the editor at some time in the past, they would expect Neil or Martin to visit everyone holding a copy of the magazine with a pair of scissors to snip the contribution out? I suppose it would be even worse for the editor of a daily newspaper, who might be expected to visit every fish and chip shop and every long drop toilet in order to censor the old newspapers there.

“The Moving Finger writes; and, having writ,
Moves on: nor all thy Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all thy Tears wash out a Word of it.”

(Omar Khyyam)

Thread: Is this doable?
17/09/2020 11:28:08

File it with a round swiss needle file.

Thread: Ally bike cranks
16/09/2020 20:50:54

I sawed one open with the idea of using the material once. It turned out to be cast, and had so many blow holes and pores that you could almost say it was hollow. Naturally it was discarded!


Thread: triple expansion engine piston rings
16/09/2020 20:48:40

I hadn't realised that the Bolton has gunmetal cylinders. Would brass rings run OK on that or are the materials too similar? Cast iron will run happily on cast iron, but that is about the only thing that will run well on itself.

On the split piston thing, if a ring is stiff enough to need a split piston to be installed, then it is too thick to do any good anyway. They need to be flexible enough for the gas pressure behind them to give the sealing force.

O rings are fine for this sort of engine, especially since they don't usually do a lot of work, much less than a typical; model loco for instance. You do want a good smooth finish on the bore.


Thread: Diamond Honing Wheel Setup on ML10
16/09/2020 15:47:42

My own machine was purchased by my late father nearly forty years ago, and is an Accu-Finish. I see they are still going. I have no connection with them, apart from being very satisfied with the machine.

If it is hot enough, the diamond will oxidise to CO2, which is even less abrasive than graphite!


Thread: triple expansion engine piston rings
16/09/2020 15:36:00

Cast iron rings made by the Chaddock method are very good, but that section is too thick and you would never be able to spring them on over the pistons, especially if the smaller pistons have the same groove size. If it was mine I would be making new pistons with grooves according the proportions suggested by Chaddock.


Thread: Diamond Honing Wheel Setup on ML10
16/09/2020 07:19:27

I've got a purpose made diamond hone setup made by an American company and that actually turns its wheels quite slowly. The wheels are used wet, water with a little wetting agent. I don't think diamonds need to be used at any great speed, bearing in mind that diamond will oxidise in air if it gets hot. The final hone with an 1800 grit wheel gives a mirror finish on HSS or carbide.


Thread: Use of 2 front wheeled motorcycles on the TdeF
14/09/2020 22:41:17

The usual rule of thumb is that a three wheeler of any sort will combine all of the worst features of both cars and motorcycles, without including any of the good features. The tricycle layouts, both forward and reversed for instance ensure that if there is a pothole, at least one of your wheels will hit it.


Thread: Strength of Beams
10/09/2020 22:17:15

It gets worse, because for the same weight of material, by making the webs or the wall thickness thinner, you can make the section larger, eg a larger diameter tube with a thinner wall, or an I beam that is taller, like the castellated beam achieves. But if you go too far with this process, the compression side will become very prone to buckling. It is quite hard to predict at what load buckling will occur, since it depends on initial straightness and whether the load is applied truly along the axis.There are ways to reduce the chance of that, for instance by corrugating the walls of the tube along the length. Of course none of this is very applicable to a boring bar, which has to fit inside a given starting hole.


Thread: J A Radford; Improvements and Accessories For Your Lathe
08/09/2020 04:50:39

I would suggest that a visit to Diamond Harbour itself might be more suitable, it is a very scenic spot on the Lyttleton harbour opposite Lyttleton itself. There is a scenic drive around Banks Peninsula to Akaroa (originally a French settlement) that could make a good days drive.

Hopefully by next year the border might be open!


Thread: Faceplate workholding.
01/09/2020 11:31:37

Put a piece of paper in between the faceplate and the job. (It will need a hole of course) This will greatly increase the friction between the two. Also a good idea when holding jobs in the vice for milling or shaping.


Thread: Ammco 7 shaper
29/08/2020 23:49:01

Mine is missing all the bits shown in your picture. They have been replaced by a very home made looking setup, which includes an extension on the end of the main shaft with an eccentric on it. Still, I don't think there is anything in your picture that I could not make.



28/08/2020 05:36:30

Back again, I had another look and even if you did get the ram off the top, you would still not be able to get at the bull wheel and shaft very well unless you took the slotted arm off. Since you can't get at the set screws for that except from underneath, it would seem that taking the column off the base is about the only way to do it.

You mentioned having a brochure, I wonder if it is the same one I have got. Mine is labelled

No 27-100


7" precision shaper for metalworking

Instruction manual


There are two pages of operation and then a parts list along with some diagrams showing the part numbers. I can easily scan it if it is different to what you have.


28/08/2020 04:03:50

Hi John, Having taken a look at mine, I find I am not sure about how I got it apart to get at the bull wheel bearing. The sticking point is the little link inside the ram linking it to the slotted arm. To slide the ram off, you would need to somehow dismantle that, and later reassemble it, and since there is no access I can't see how that would be done. With some machines you would be able to take an extra large gibb strip off the side and that would give enough clearance to lift the ram away, but that will not work on this one. It is over twenty years since I had it apart!

Still even if you do have to take the column off the base, the parts are at least lighter than with bigger machines. On my !8" Alba, the slotted arm alone would weigh as much as the AMMCO.

Yours does have the original fine feed, mine has a not very good home made one done by a previous owner. I wouldn't mind sketches and/or photos of the bits if you felt up to it. Yours is later production than mine, as it has the table height hand wheel out to the side. Mine has the wheel underneath the table, the screw is long enough to poke through. There is no easy way to date these machines, but they started in the thirties and stopped I think in the early sixties. The motor unit on yours is similar to mine, except mine uses a flat belt for the final drive. That may have been a mod on yours .


Thread: 6" Stainless Steel Pipe
27/08/2020 23:19:34

There is a length of stainless tube at Scrap Palace in Hamilton NZ, about six inches or so diameter, and maybe 3/16 or so wall thickness. They would happily sell you the whole length, maybe 3 or 4 metres but I don't think they have the means to cut it. I didn't have any measuring equipment with me but they could measure it.

John (in sunny Cambridge NZ)

Thread: Ammco 7 shaper
27/08/2020 21:20:59

I have one of these too. They were made at first under the AMMCO name, and specified as six inch, but later on they were acquired by Delta Rockwell and were specified as seven inch, without any changes to the actual machine. I've made up a copy of the dividing attachment, and I've got a copy of the original vice partly machined. The old Yahoo shapers forum had a lot of good discussion on them, I don't know if that material can still be tracked down. Some effort went into trying to work out how the serial numbers worked, to no particular conclusion. If it is labeled AMMCO it is earlier, if it is labeled Rockwell it is later.

I did have mine apart once to allow me to make and fit a new bush to the main shaft, but I don't recall any particular difficulties. I'll take a look at the machine and refresh my memory later. With most machines, you take the ram off the top first, then remove the slotted arm, and that lets you get at the bull wheel. After that, the mainshaft can come out.


Thread: Simpling / Starting Valve Help Sought
26/08/2020 22:51:41

Like most things, there are more than one way to do this. The simplest is just a valve that lets you put a shot of HP steam into the LP cylinder. As you say, this will put back pressure on the HP, but since that was presumably on dead centre, that won't matter, the LP will kick the engine over and off you go. That is what I have done on my steam launch.

The other approach is a more complex valve to divert the HP exhaust to the stack (or condenser) and apply HP steam direct to the LP cylinder. This would be a better approach for an engine that has to start and pull a heavy load, maybe up a grade for some time, like a traction engine or a locomotive. It does need a much more complex valve arrangement. That could affect the steam flow at high speeds, but that is not likely to be a concern on a model, which is not going to be looking for maximum power at high speed for long periods. In simple mode it will of course give greatly increased steam consumption, but since it would only be used when going slow, that should not be a problem.


Thread: Super sopper
26/08/2020 00:14:51

I'm surprised that they would need such a thing in Australia. Some means of putting out fires on the pitch would seem more useful there.


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