Member postings for Russell Furzer

Many thanks for all this advice

Encouraging enough to do the hydro test

I have acquired an old scotch marine type boiler that appears to have been well conceived and made. It is from copper seamless tube, 5” for the shell, 2” for the main furnace tube, 6x 5/8” smoke tubes. Three stays (copper). The end plates are flanged and riveted both to the shell and furnace tube. All ? caulked with what i reckon is soft solder.

The builder is unknown and the provenance is from a deceased estate.

My initial thought on deciding that it was probably soft solder rather than silver solder was that it was too risky to consider seeing if it could be brought into service, but on the other hand i’m loathe to scrap it when my impression is that it is well made. Material sizes, numbers of rivets etc would seem to comply with KN Harris when he discusses this type of construction (and then gives examples st 100psi!! I would aim at 50 or 60- running a D10 or 10V)

I imagine that the way to proceed is a series of hydro tests? Is there a benefit to moderately heating the whole construction (all ports open) in an oven (200C or so) then allowing to cool between hydro tests?

On the other hand, if there was universal opinion that it was too risky ever to steam, then the effort in setting it up for testing can be avoided.

Final point- private risk only- never to be steamed in public

I have been reading an ancient ME from 1953. Author "LNWR" has an article describing making jigs to cut valve ports.

The gist is that the first jig is held with a clamp and guides drilling the holes for studs to eventually hold the steam chest (and before that locate the second jig). The first jig also guides drilling most of the meat out of the valve slots.

So far so good.

The second jig has correctly sized slots (made by filing) and has matching punches to cut the ports. The described use is to scribe the outline of the slot and then remove the jig to "CHIP OUT THE SLOTS AS NEAR AS POSSIBLE" thence replace the jig and follow with the punch (which is dead square on the end)

How do you reckon the author would have gone about "CHIPPING"?

Article in Vol 108 no 2696 page 116

https://archive.org/details/Model_Engineer_Vol_108_No_2696/page/115/mode/2up

Edited By Russell Furzer on 13/07/2022 12:42:24

I have found an apparently nicely constructed copper boiler in a junk store. It looks home-made and is along the general lines of a ST 501.

I am 99% sure that the solder is proper silver brazing, but wonder if there is a test that i can apply?

I understand the sequence of pressure testing and will do a cold hydrostatic test before talking to our local AMEB inspector

If the solder is not correct (or if it fails the hydro test), i wont bother him and will scrap it

I have tried hopper's method in the past with satisfactory results.

An alternative is to find a bit of tube that is close in ID to the diagonal size of the bar (i.e. root 2 x dimension), make one longitudinal split, put into the 3 jaw, bore to the diagonal size, pop in the square, gentle tighten and Bobs your mamas brother.

It might allow sort-of indexing if a thin cut-off type blade were held

Hi Muzzer

I do have a milling vice. But holding the round bar between flat faces didnt seem as secure as the tool holder.

I didnt use the tee slot because I wanted to access all of the end of the bar without hitting the edge of the slot.

The QCTP holder was very easy to set up too - I posted because I thought that this was a good solution to the job that I had on hand and that others might consider it as an arrow in their quiver.

I have just had a task requiring the holding of a 5/8 bar for milling and used the boring bar holder from my AXA tool post to hold it. Clamped the thing to the mill table. worked a treat.

I hate painting. I painted my 10v with green enamel spray paint that I had bought for a Lister diesel (full scale) project.

I sprayed a splodge on to a saucer and then used a paintbrush. I had degreased the surface first but didn't prime it.

I was quietly pleased by how good the outcome was, and has stayed. Luck rather than judgement perhaps

G'day

I'm pondering the order of operations for assembling a scotch boiler. Copper. Silver solder.

I have seen descriptions of soldering the tube plates to the shell as one operation and then soldering in the tubes as a second.

The alternative is to assemble the tubes into the tube plates then solder that assembly into the shell.

What is the best way?

If the slot is long enough then you could use a feeler gauge on its edge and measure how much sticks out

I want to remove the left hand bearing on my AL960- to get to the sliding gear. The parts list shows a bearing cap then a nut ( locked by capscrews closing a slit).
Is it a matter of removing the bearing cap, marking the position of the nut, taking it off and the bearing slides off?
Is resetting the preload a matter of putting the nut back where it was ( like a Salisbury diff)?

The issue of whether a brake would be useful is germane. I haven't 'needed' one either- haven't got one. I would like to know whether those who do have them report an advantage.

would a better design be worthwhile?

Thanks for the reply.

a brake on the back of the spindle itself might be better then.

No probs with the unscrewing chuck - mines a D1-4 cam lock .

I agree that the brake on the spindle would seem the best place for it - thing is thats NOT where they seem to be fitted on similar sized machines. The usual place is the pulley on the input shaft.

My concern would be that the load would then be taken via the gearbox. Not sure if thats a problem.

Probably the reverse would happen with the brake on the spindle - the load to decelerate the (switched off) motor would be taken through the gearbox. Wonder whether a chuck has a greater inertia than the motor or vv.

Surely someones done this? My googling came up with one article from 20y ago about a pulley modified to be used as a brake in the same manner as the chinese lathes and a 1955 Pop Mechanics article in which the brake is on the motor shaft itself/

Is the whole idea a waste of time perhaps?

I have a AL960B lathe - 305x960. The supplier also sells a Chinese lathe the same size that comes with a brake that works on the pulley on the lathe end of the motor drive belt. The spindle is then stopped via the geared head.

i can see some utility in such a system- more so with an electronic actuator that might be part of a system that can be activated by a limit switch- allowing threading to a shoulder etc. I can imagine a suitable control circuit.

is such a brake of value? Has anyone here made one? Would it not be better to brake the actual spindle (to avoid sudden loads via the gearbox)?

Thanks for the reply Brian

I must be a bit dim, but can't work out where 300 and 1000 come from.

The cutting surface speeds ( I looked at 3/8 and 5/8) works out to be 62.83fpm for 4 flutes, 100 for 2 flutes at both dia.

If Tooth Load = Feed Rate/ (RPM x No teeth) then the TLs are double for the 2 flute (.001" vs .002 for 3/8, .002 vs .004 for 5/8) .

I presume that a factor of 2 is not an issue for the home workshop. The figures seem to work out ok for me when I blindly use them. Better not to think too hard i suppose

In the ME Handbook, pg 5.14 there is a pair of tables for 4 and 2 flute cutters.

the 'tooth load' of (for eg a 3/8) slot drill is higher than for and endmill - is the table right?

Pete

I dont think the wisp of flame out of the flue is a secondary air issue - there is a right roaring flame at the other end - I think the flame just has too much volume to fit in the flue. My 'radiant' stainless cone halfway glows a treat and the test flue goes red-hot.

I think that the design is probably OK and that I need to consider the heat exchange of the return flues to make sure that the heat is used. That does make for a much more complex testing setup for the phase ahead.

Russ

Thanks Pete.

same had occurred to me, but I have choices bigger and smaller but no goldilocks! The 7kw sievert makes the test flue look like something from NASA, the little portable fiddly bits one and the 'gasmate' butane ones are too small. I do have a 'mapp' ( I know it's not like the good old days) one , which is about right but the design and fuel are quite different.

What I wonder is where the gas burns in other peoples boilers- is it in the primary furnace tube, or in the return flues, or - heaven forbid- out the stack.

Also Pete- how big is your boiler? What size burner jet have you? How many and what dia are the return flues?

Edited By Russell Furzer on 02/06/2014 11:38:23