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Member postings for Robert Dodds

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

Thread: Silver solder? ....... or what?
26/06/2021 22:15:30

My guess is one of the several varieties of SIF bronze. Father in Law used to use it for repairing cracked Cast Iron with an oxy-acetylene torch . It's Silicon Bronze with a dash of of silver and tin in it There are lots of suppliers still around, . give one a call to check the colour coding.

Regards Bob D

Thread: Pulley size help required.
18/06/2021 12:21:36

Old mart,

Your photos show your Atlas to be a later model than mine and I'm glad you can see a solution.
A note of caution regarding your speed range with the 3" pulley on the lower speed pair. You will then have raised your lowest spindle speed by 50% (3" instead of 2" > This may suit your purposes Ok but it depends on what your motor speed is and the type of work you will be doing as to what part of the overall speed range you will use.
I used an online belt length calculator ( https://www.omnicalculator.com/physics/belt-length ) and from it, assuming my scaling estimate of 8" for your centre distance in the photo is right and presuming a motor speed of 1400rpm your 2 choices of layshaft speed would be 466 or 985 rpm.
If you opted to keep the 2" pulley and fitted an inch shorter belt ((35" instead of 36" as indicated for 8" centres) and then made a 4.4" dia. pulley as the larger drive pulley you could expect a slower and wider ranging layshaft speed of 311 or 823 rpm.
As I noted before the choice depends very much on what your expected work range is.

Regards Bob D

Edited By Robert Dodds on 18/06/2021 12:24:06

Edited By Robert Dodds on 18/06/2021 12:49:20

Edited By Robert Dodds on 18/06/2021 12:50:33

16/06/2021 20:39:11

Question.

In my photo is the belt set to high or low speed ? With the second cone set to top speed it does about 600rpm with a 1400 rpm motor.

Bob D

16/06/2021 20:04:43

Old Mart,

I've got an Atlas with 2 speed primary drive. picture attached. Daft question but "do you have the motor pulley as my configuration? small motor pulley to large driven pulley, If not, try reversing the motor pulley on its shaft to look more like mine That works fine for me.

Hope this helps

Bob D

  1. atlas pulleys.jpgrt,

Thread: A bit more upcycling.
12/06/2021 21:33:34

Like it, A lot.

Bob D

Thread: Does anyone know what this is for?
09/05/2021 21:07:28

I think I can see two rollers, one at the handle side and another at the opposite side. Both have semi circular profiles and in one picture there may be a third roller which looks to be horizontally mounted in the same plane as the other two. I ask if this could indicate some form of wire bead folder similar to that which was used in auto construction in the 1930s.
Looking at images of bead forming machines highlights functional similarities between our mystery tool and some of the more recent designs of bead roller.

One maker has a video of making a bead rolled edge on a vintage Ford body panel that's well worth watching.
https://www.youtube.com/watch?v=eOcZwr-1Y1E

I can't explain the purpose of the outboard rollers but I think the primary tooling is hiding inside the head somewhere and that the hand lever is used to relieve pressure (from the big spring underneath) whist loading the part to start whatever.

Hope my musing makes sense to others

Bob D

Thread: Oofle Dust
03/05/2021 19:40:10

After a minor mishap with the domestic formica worktop I got away with a camouflage of epoxy and an oofle dust from the ladies nail bar, where they have mica powder in multiple colourways that can match the chipped corner. My supply came courtesy of the greeting card production line where the same oofle dust is used to enhance the greeting cards.

Bob D

Thread: Alternative back gears
28/04/2021 20:37:29

Carl,

How closely does your 80T gear match the diameter and width of the big gear in your dreadnought photos. Assuming it is close you will require to bore out and add the slot for the drive peg if you are going to use that one but it's more important to establish the centre distance between the headstock spindle and the back gear shaft because this will determine whether you can use that 80T gear. The centre distance may indicate that you need a 11 1/2 tooth gear and that's a bit impractical!!.
The sliding back gear presents a different problem. Counting the teeth I can see, I'm guessing the large gear is about 40 T, way different to the bull gear behind the chuck. It looks as though the small gear with damaged teeth on the sliding gear assembly is an integral part of the slider, it may be a press fit in the 40T? gear, but either way not an easily replaced part.
If you are looking to use standard, off the shelf gears you may consider altering the gear configuration to the simpler sliding and rotating back shaft that is used on many small lathes.This could involve pinning the 40T to its shaft and getting the mate to the bull gear similarly pinned to the back shaft.
Again, as others have said,. you must start by getting the centre distance of the gear train and then decide on your gears from there.

Regards Bob D

 

.

Edited By Robert Dodds on 28/04/2021 20:39:57

Thread: Portable vice - buying advice sought
28/04/2021 16:59:51

John,

Google
clamp on swivel vice.

There are lots to choose from but beware any profiled edge on you table as the throat of some of the G clamps is not huge and could reduce the stability of the vice in use.

Regards Bob D

Thread: Help please!
28/04/2021 16:41:10

Diane,

Nigel mentions Model engineering Societies. As you mention Nantwich there is the South Cheshire MES who meet at the back of the Peacock near the Nantwich bypass. They have a website with contact details on there and may be able to offer you some local advice /assistance.

Regards Bob D

Thread: Four facet drill grinding.
26/04/2021 20:45:26

Is the reprint article of Giles Parkes of any interest

From the Archives: Twist drill Sharpening by the Four Facet Method

Model Engineers' Workshop|May 2020 No293

The original article was published in 2000 MEW 64.

Bob D

Thread: Does anyone know what this is for?
26/04/2021 10:24:57

Am I seeing a hand cranking lever and a couple of gears on the far edge of this machine. If it is, it suggests to me that there was a fair amount of manual effort involved in whatever it was doing.

Bob D

Thread: Drunken pulley
15/04/2021 21:23:51

Martin,

Are yo sure the wobble is in the pulley and not due to the shaft that it sits on being a bit bent?
At least check the shaft for concentricity before boring out or modifying the pulley
Bob D

Thread: A Manual of the Hand Lathe
08/02/2021 21:04:19

Michael,

A very interesting book to browse in . Thank you for bringing it to the forum.

Tim,
On the question of thread chasing, I was employed in the early sixties by a well known manufacturer of "gentlemen's toilets". Their "brass shop" produced lengths of threaded copper pipe which were assembled to cast brass Tees or Crosses to form the down pipe for said toilet, all being screwed and soldered together before either polishing or chrome plating.
The pipe threading was entirely done with hand chasers usually with a mandrel up the pipe to provide support and all to 26 TPI. Once started the multiple threads on the chaser ensured that the pitch of the thread on pipe was correct
One of my projects of the day was to introduce brass stamped Tees and Crosses with silver soldered joints replacing the screwed and soldered version.

Happy days,
Bob D

Thread: Metric thread sizes
31/01/2021 12:56:27

pgrbff,

Your motor mount picture clarifies the configuration quite a lot.
Have you still got the 1/2" rod? Seeing the type of motor mount you have I suspect that the bend in the rod is intentional to accommodate the curved movement of the adjusting lug as the motor and plate pivot on the hinge at the bottom.
It may well be a cheap compromise to avoid using an eye bolt and clevis that would, in an ideal world, enable the screwed rod to be held square to the face of the adjusting lug.
In service there is no way that the forces involved with tensioning the vee belts would over stress your 1/2" rod, unless of course, the threads are badly damaged to start with. With that proviso I suggest you do a trial assembly and stop worrying about high tensile rod replacements.

Regards

Bob D

30/01/2021 20:13:32

pgrbff,

Do you know how this 1/2" rod got "bent"?
Your machine is unlikely to have more than 5 hp driving it and it is difficult to imagine that a motor of that size causing the damage. It would be more in keeping with an accidental collision with a fork truck or similar handling equipment
Is the rod used as a belt tensioner?
Unless you are constrained by having 1/2" tapped holes in the motor or machine frame consider substituting M12 studding with appropriate nuts for the present rod. At least you should source that in Italy.. As far as strength goes, M12 studding should have the capability to carry at least 2 tonne, more than the motor weight and any belt tensioning that is involved bu obviously , if other outside forces are involved some damage may result.
I googled Antique bandsaws and the images that came up show a great variety of makers and sizes and some with the motor floor mounted rather than on the machine. Would this configuration help with your project?
Hope this gives you some food for thought.

Bob D

Thread: Retro fit heated window elements
10/10/2020 21:30:11

Hi CT,

Looking at the instructions with the kit contents in your LINK I think you will require two more of the vertical strips if you are going to fit out to two windows. My guess is they make contact with only two of the three strips at each end.
I note one spade connector is up and on the other side is pointing down so you end up with three lengths of triple wire tape forming the circuit.

I guess you should see if Holden will supply you with two extra vertical strips to let you use your spare element strip on a second window and then wire the two assemblies in series to avoid the chances of overheating.

HTH
Bob D

Thread: COMPRESSION RATIOS
30/08/2020 17:07:46

Redex used to market these for checking compression through the spark plug hole. Most useful on multi cylinder engines to check for burnt valves or broken rings.wp_20171022_17_14_32_pro.jpg

Bob D

Thread: Grayson Lathe refurb
16/08/2020 17:41:45

Jim
Are you aware of the detail on Grayson (and many other) lathes on archive website
http://www.lathes.co.uk/grayson/index.html
It also points you in the direction of a book, The Amateur's Lathe, avidly read by many.

Bob D

Thread: Hot Buildings and expansion.
15/08/2020 22:26:57

Plasma,
I don't dispute your Blackbird story but how do you decide whats leaked away and whats burnt when you're doing Mach 2?.

Pattern makers still have separate rulers with allowances to suit the metal being cast. Chesterman Rabone offer a set of 4, one standard and three to suit Iron, steel and brass. (aluminium alloy is generally the same as brass). Trouble is there are far fewer local foundries than in our forefather's days so you don't see many of them nowadays. You got to go East to find them today.

Mike,
Not only temperature has a potential impact on machines. My head scratcher was a multi head driller that misaligned with the seasons and that arose from the building having been built with one corner on a wet clay bed that expanded in the wet winter months and induced a twist into the suspended first floor where the machine was sited and then shrank through the summer months. Pneumatic isolation mounts with just three reference points sorted it out but the machine did lean a bit in the winter!!
But the holes were in the right place.

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