Member postings for norm norton

This is a bit of a specialist question, but perhaps a fluid flow specialist might know the answer, and others might like to speculate.

I have built a pair of safety valves for a 5"G locomotive, and to make them more prototypical in appearance have drilled the vent cap with two rows of very fine holes (18 off 0.9mm dia. and 18 off 1.2mm dia.), rather than a single row of larger holes (12 off 1.7mm dia.). Now the cross sectional area of my two rows is substantially greater than the singe row, but I am concerned that the diameter of the holes is such that they act as critical flow orifices. However, if the flow through the single row is not supersonic, it cannot be so in the two rows. Or am I missing something?

I have used this website that provides a calculator https://www.tlv.com/global/TI/calculator/steam-flow-rate-through-orifice.html

but if I plot the data for smaller and smaller orifices I still see a liner flow vs. area response, so has this calculator allowed for a critical behaviour? I don't think so but what do others think?

I appreciate that I could answer this if my physics knowledge included Reynolds number and fluid physics, etc. but it dosen't. Anyone have a quick answer? Sorry I don't have a ready number for the mass of steam that the valves have to shift other than an estimate that we are talking about 10 to 20kW of thermal energy generating that steam.

Norm

Dave Noble is around and active. I don't think he has a connection with The Steam Workshop, nor am I aware does Doug's son. Dave has cut out all his previous, extensive manufacture of engine and wagon parts, but last I spoke to him he was continuing with the water gauges. He did supply several retailers, try Blackgates first.

Jeremy,

Could you get on with just having all Metric screws and bolts in your stock, and then buy any special UNF/UNC/BSF/BSW/BA only as and when needed? I would now recommend any younger newcomer to convert any drawings to metric and certainly the fittings.

I do like imperial, but I have BSF/BSW in zinc and stainless for motorcycles, and 26CEI for engine parts. Then an awful lot of BA in brass, steel and in hex, reduced hex and slotted. My Allen Head and Grub Screw box contains BA/BSF/Metric sizes in steel and stainless. And then, of course, I have a whole range of Metric screws and nuts in zinc mainly to cover the sizes above BA. And I still end up turning custom screws and nuts for steam engines which need 32 and 40 TPI.

It's all a bit too much really. Plan all jobs in Metric and stock those only. Buy good sets (Tap and Die Co) of all the other thread forms for the specials, and you will be fully equipped.

Yes that was a good little video to see, thank you.

It appears that rolling the balls repeatedly up a series of spiral channels eventually forces them to self wear and become spherical. I wondered if any grinding paste/suspension was included or if their own grit did the job? I think they mentioned lapping paste for the final polish.

I thought I read many years ago that early ball bearing manufacture involved dripping molten steel from the top of a tower, with the molten steel forming a ball before it cooled and hit the sand at the bottom? or have I muddled this with another process?

I think that Britain has never (?) had its own ball bearing manufacture, which is why we were in trouble for the two world wars. Industry was using imported metric bearings in the 1930s because you find them in otherwise fully imperial motorcycle parts.

Thanks for all your help, it's now running again after taking it all to bits and reassembling.

I apologise for for jumping to the wrong assumption that the PCB or motor had failed, when I should have checked the wiring first. I apologise to Mr Sieg for spelling his name wrongly in the title and my text (I before E except after...) I apologise to Ketan for wasting his time with his kindly offering to help.

Yes it is a 2008 machine with the later aluminium end to the motor. I took that off, checked that it ran on 12v and it drew just 80mA, so that seemed ok. I took out the PCB and could see no surface evidence of overheating. I then worked out where all the wiring went through the switches and measured the resistances - no breaks found. Hmmm. Lets put the PCB back in as a lash-up and connect the motor again to see if there are any volts at all. Oh, it now works!

So, a whole day and somewhere in the process I have cured a poor connection. I would guess it might have been in the cut out switch circuit - I had many years ago removed the chuck guard and joined those wires to the switch together, but perhaps not very well.

Edited By norm norton on 06/06/2020 18:02:45

I have just found Les Jones' website with information on his X3 motor that he took apart in 2008. It is a two wire DC supply, 13 slot and 39 segment brushed motor. DC 230v max, 600W, 3.2A. It seems I can test it with a DC power supply and watch for a smooth current draw of up to 200mA at 40v with no load. So I will do that next. Apparently if the motor has a failed winding it will have popped the PCB.

I have had a call from Ketan at ARC and he has been really helpful. Apparently I might have one of the longest running and oldest X3s and it has probably benefitted from my humidifier dried workshop. He has motors available and has kindly made enquiries about getting me a controller.

What he does not know is whether any other, modern DC power supplies will work. Fair enough, you need to be a DC brushed motor expert. Anyone out there have a view?

Edited By norm norton on 06/06/2020 12:32:01

Thank you Chaps. I will have a look at the PCB carefully for a broken section. I think also I need to note down a few details about the circuitry and see if one of the Chinese £25 controllers will wire in, or I follow my new inclination to avoid China and support the British company.

I assume I can just put 12v DC across that motor and see if it drives forward and reverse smoothly? I guess it will want to suck a few amps so I would use a battery rather than a power supply. The label says - ZYT-600 DC 230v 600w 4000r/min 3.2A CLASS E FORWARD. I am not sure what the 'class E forward' means?

I have a nice old Seig X3, bought more than ten years ago from ARC, in the days when you had to take them apart and clean it all before switching on!

It has been a good machine and I listened to others' reports of motors failing and thought, well maybe one day.. and that day has come, perhaps.

I know there are a few X3 users on the forum so I am asking if anyone can comment from personal experience. I know I can contact ARC and will do that next.

Yesterday I was running the motor at maximum speed for a 1mm drill and switched off by putting the forward/reverse switch to zero, which is what I usually do. Today I get the green power light on the front motor panel, there is no yellow trip error, and the single fuse I have tested as ok. I can switch on in the 'wrong' sequence and cause the yellow error to light, and clear it, but no power to the motor and no noises whatsoever.

Looking at the PCB in the back it all looks clean and I can see no overheating.

So have I got a failed PCB or a failed motor? Anyone got some tips for simple circuit checks to look for volts or continuity in the motor?

I wonder if ARC might carry parts? I have thought in the past about fitting a half horsepower 3 phase motor and VFD if mine ever went pop. For now I would just like to get the DC motor running again.

Thanks,

Norm

Choo, I agree with your thoughts to want to try and understand what goes on with paints. We need someone who has written a book on the history of paint to comment, but I doubt there is one.

I agree with some of what you have said, but not all. Here is my summary of understanding. I have messed with paints for forty years but I have no specific competence in the subject.

1. Traditional paints were called 'enamels' and were pigments ground up with oils and resins of animal and plant base. Designed for brush application. The solvent was turpentine and more recently white spirit.

2. Natural materials have been replaced by synthetics (chemical industry products) and the word alkyd appears. Synthetic enamel can be thinned with white spirit but synthetic thinners is available. Toluene is a constituent. Synthetic enamels dry more quickly (which can make brushing more difficult) and are relatively easy to apply by spray because of this.

3. Cellulose paints were (I think) developed purely for spray application (1930's?) and were quick drying for industrial speed. You cannot brush apply because of this. The solvents are based around cellulose acetate. Cellulose thinners is a powerful solvent and will dissolve and melt most other paints. Hence, never put a cellulose paint on top of other paints or primers.

4. The automotive industry moved away from cellulose base to polyester many years ago. You cannot buy cellulose paints now (generally) and for home spraying it is polyester and a slightly more friendly 2K thinner. Gloss polyester is mixed with an activator (urethane or isocyanate reaction?) to make it harden. The solvents evaporate more quickly than cellulose. It sprays easily, drys fast and is much more durable than cellulose (modern petrol resistant) The majority of car respray systems involve a 2K clear lacquer topcoat. Safety breathing equipment HAS TO BE WORN. The car world has moved to water based paints and this will also arrive for home use, which will be a good thing for spraying, but not so for brushing perhaps.

The above relates to top coats. There is another subject on etch primers and on undercoats.

Edited By norm norton on 27/05/2020 09:58:53

Roger,

Yes, fully support your thoughts of an SX but go for the SX3 like Adrian at £1640. It is 70% heavier than the SX2.7 and mass is a good thing in milling machines. Both come with an R8 spindle which is the best choice for a home workshop.

Enjoy it! and then plan to fit a quality DRO!

Norm.

When I first saw this yesterday I also wondered for a second or two what the meaning was. Then I recalled that the eminent person describing it was an anaesthetist, as well as steam engine rescuer, and I would trust him totally. The more you think about it the more sense it makes.

RMA thank you for making me go back to square one and recheck. Maurice I owe you an apology and I am sorry I was wrong and you are right.

I am grateful that this forum discussion has caused me to find out the facts and it will be a big help to me when I have to renew at age 70. I have been led astray by friends who told me that I would lose my over 3.5 tonne GTW (Gross Train Weight) towing rights at age 70 renewal - they are wrong. A confusion has been that post 1997 licences only have category B and that this is restricted to 3.5 tonnes GTW. However, pre 1997 licences also have category BE, in addition to B, and this BE permits the vehicle MAW (Maximum Allowable Mass) to be up to 3.5 tonnes and for it to tow a trailer upto the vehicle's plated limit, just as RMA says.

At renewal at age 70 the pre 1997 licences retain category BE.

Thank you to those who were patient enough to tell me this. You have saved me going through the forms D2+D4 palaver.

No, not any size of trailer. Only up to a combined vehicle + trailer weight (MAW) of 3.5 tonnes.

A VW Transporter for example has a MAW, or gross vehicle weight, of between 2.5 and 2.8 tonnes depending on specification. Most caravans, or trailers capable of carrying a small car, will easily take you over the 3.5 tonnes total.

That is an excellent document, thank you.

To reiterate, if anyone is like me under age 70 (just) and holds a driving licence issued pre-1997, the licence will include categories C1 and C1E(107) which permit that driver to use a vehicle and trailer where the combined GTW is over 3,500kg. I make the point that a number of caravaners and others fall into this group of individuals. C1E(107) differs from C1E in that it downgrades the maximum GTW to 8,250kg.

At licence renewal at age 70 those C1 and C1E(107) categories are lost IF one does it online or at a Post Office WITHOUT additional documents. These are forms D2 and D4, one of which has to be signed off by a doctor, and there will be a fee for this. The forms have to be submitted by post or through a Post Office. The licence has to be renewed every three years and the D2+D4 process repeated.

Edited By norm norton on 06/02/2020 10:45:05

Thank you Pete for finding that. Hmm, looks like you have to pretend you are a lorry driver, and I guess go through the same hoops every three years after 70?

Thanks Michael, I thought you were querying or adding some information.

That link is the DVLA description of licence categories. I am referring to categories C1 and C1E that are on my licence, and many others, these having been referred to as the 'big lorry' up to 7.5 tonne MAW category that people may decide is not needed past age 70.

My reason for posting is to warn those who regularly tow something that it is very easy to exceed 3.5 tonne GTW.

What I have not seen published is the fact (?) that these categories are routinely removed at licence renewal at age 70; it must be written somewhere. And how to retain them. I was reporting what others have said to me and would like to see the official text.

Norm

I see that no one has mentioned towing something and the combined maximum weights being over 3.5 tonne GTW.

Us old boys have rights in our pre-70 licences to pull a big caravan or trailer with boat, etc. behind a large 4X4 or small truck or even a van like a VW Transporter. It is easy to exceed 3.5 tonnes GTW (Gross Train Weight).

As I understand it that permission is lost at age 70 renewal, unless you apply in writing for the new licence with a letter from a doctor stating you are fit to retain that over 3.5tonne licence category.

Mark

I fitted a 2 pole three phase motor and inverter to my 140. I spend most of my time working it at 25Hz (half speed) but the motor will wind up to full speed, to double the lathe single speed, which the 140 was designed to take. You can even get a 140 two speed plate to put on the front.

Norm

1/32" seems rather thin for such wide 3/4" spring leaves. Is this for a model, a steam engine? Smaller 3/8" wide springs would use about this thickness.

M-Machine sell 3/4 x 16swg ( 1/16" ) spring steel strip for £3.30 per foot, and 3/8" in the thinner gauges. I would make 3/4" springs from this.

Edited By norm norton on 26/01/2020 11:18:54

Hewson discussed the springs for a Britannia in ME210/4453p526.

There is something about weights and adhesion theory in ME211/4470p808

The issues are using the right steel in its tempered state, then hardening and tempering for springs. Then deciding from the model weight what the correct loading is per axle, and how much compliance (spring rate) is best, and measuring the deflection obtained (ideally in a test jig). Because 100% tempered steel springs are often too firm for an application, there are options of substituting some leaves in Tufnol, using bronze instead, or machining slots in the (soft) steel leaves.

I don't think I have seen an article attempt to address all of this. But if you search the Model Engineer Clearing House Forum http://modeleng.proboards.com (best to do this through google 'leaf spring modeleng.proboards.com' ) the subject has been well discussed in recent years.

Norm

edits - killing smilies !!

Edited By norm norton on 15/01/2020 14:28:53

Edited By norm norton on 15/01/2020 14:29:21

Edited By norm norton on 15/01/2020 14:30:21