Member postings for Paul Kemp

I bought from Allendale (I believe) at Ally Pally MEX probably in 2016 a 12" calliper on offer for about £50 as I didn't have anything of that size to assist with my half size TE build. It had very little use really only being used for machining ops on the larger bits like diff housing and brake drum etc. I bought in preparation for those parts so didn't get to really use it for about 6 months and before it was a year old I found when sliding closed to check zero it regularly started to jump. Initially it was only small amounts (less than 50 thou which almost caught me out!) but as time went on by inches! Tried cleaning, battery changes etc but nothing seemed to cure it. Any ideas what caused that? I can't follow up as its well out of warranty and it then befell an unfortunate incident where it was on the headstock of the lathe and the machine lamp drooped close to the case and melted a nice depression in it! Typically over the reading head! Opening the box it was very warm and the display had gone completely black! When it cooled down the display returned to normal so I thought I would try it, still functions but still jumps! Looking at it there appears to be play in the measuring head so the moving arm rocks slightly, not good for accuracy anyway but it appears when it rocks it jumps! I can't see any way of adjusting the play out so it's really only fit for the bin! Would be interested if anyone else has had similar experience though and the cause?

Conversely I have a ladle unit that must be 15 years old and is the go to instrument for anything not of high precision. I calibrated it with slip gauges in December out of interest and was quite please it is not more than half a thou out over its full range. It probably gets a new battery every 18 months. Great value for a cheap supermarket item!

Paul.

You don't mention what machinery you have but consider looking for a slotting head for your mill if you have one. Will be way more than £100 for a broach but you will be future proof for any other sizes (and potentially shapes other than square going forward! It's a sad fact of life that time has to be expended either in making specialised tooling or setting up to use it - it's all part of the process

Paul

Paul,

Welcome to the forum. Sadly I anticipate your post is going to attract a raft of comments from some slightly grumpy old men complaining you have not given any kind of depth of detail to assist them in advising on your problem.

You may wish to follow up now with another post giving a little more detail as to how the machines are powered, ie are they 240v single phase, true 415v 3 phase with a proper incoming 3 phase supply and meter or some means of converting single phase to three phase like a static or rotary converter would be a good place to start. Then if they are powered from a converter the type, what indications are available on the converter (power lights or meters) etc.

If you give plenty of information on the set up, and exactly what the fault appears to be I am sure there will be plenty of responses.

all the best,

Paul.

I do, but nobody wants to hear that lol, they fall in the etc category of my post.

Paul.

I don't see a particular problem either. The original faceplate supplied with my Harrison L6 is almost 2' in diameter and the slots go pretty much all the way to the edge so by implication there is an expectation items will be clamped to it to enable machining at a large radius so load on the headstock bearings could be quite large. 15kg of weight on the bearings is hardly massive. The only rider is keep the speed down to the limitations of the chuck and as Nigel says watch the out of balance forces from irregular shaped work. Not sure who might be trying to machine say a slug of 6" diameter steel bar at 1000's of rpm though!

Paul.

I would tend to agree with John. Restricting yourself to insert tools depending on what you are making restricts what you can do, for example trepanning a small recess in a face, turning small radius curves (too small for a radius attachment), machining a groove with a semi circular root, the list goes on. The ability to grind up a tool for a specific purpose on the off hand grinder including form tools will save time, money and frustration in either trying to find a suitable insert, buying it and waiting for it to arrive!

All tooling has its place, HSS, brazed carbide, inserts and holders etc. Reliance on pre shaped and ready sharpened throwaway tooling is undoubtably restrictive.

Dont forget that the advantage of the ability to grind a tool is not limited to the lathe alone! It opens up possibilities for fly cutters on the mill, tools for a shaper and you can even make your own spot facing tools for pennies and not be restricted to proportions available off the shelf.

Paul.

Lol I rest my case. Now not only is the bloke being lambasted for poor practice and leading novices astray but now his motives are being questioned as to why he decided to do the job that way in the first place! I am surprised this has not been closed down by the "authorities" early on as it potentially encourages viewing of associated content with reviews of equipment from banned (on this forum) suppliers!

Paul.

Sometimes I despair at this forum. Undoubtably there is a lot of good stuff but equally there is a lot of pointless bitching, point scoring and willy waving! Ramon, sadly you were lead into a trap here by not having the advantage of knowing what was being done or the purpose of the clamp. I don't see there is critiscm of your postings for actual machining set ups where higher forces are involved but for drilling a 3mm hole if he could have held it steady enough in the right place he could have held it with his hand! Now wait for the rush of critiscm on that last statement!

Clearly I am not alone in thinking the OP posted an extract picture with commentary that was completely out of context to the operation being carried out. For the purpose of what he was doing only a very light clamping force was required and to horse a heavy clamp down hard would have been detrimental to the casting! By all means use a valid example such as where someone is milling something held to the table with chewing gum and sellotape with a 4" face mill that clearly presents a danger to operator and machine but this example does not fit that category!

This whole thread is pointless, the video maker wasn't giving any instruction on how to use a milling machine he was merely showing how he was intending to hold an irregular shaped casting to a plate which could hold it for future ops. At no point did he advise or infer anyone else should follow his approach that I heard and I did go and watch the whole video.

Too many people on here ready to throw bricks when I am sure they probably live in glass houses.

Paul.

Having strongly disagreed with Bob in the past on various posts related to boilers I think there is small merit in his questions. I am sure with small changes such as flue diameter or even spacing there could be improvements to be made but those improvements unlikely to be in the measure of 10's of percent and probably limited to decimals of percent. Gaining better understanding of exactly what happens at our small scales can only be beneficial and others have trod the road before and not concluded there are significant gains to be made. Maybe that is because efforts have been concentrated on improving the standard fire tube, locomotive style boiler on which there is much full size information to draw from over many years rather than moving to a completely different style of boiler - which is difficult if you want to build a model of something that looks like it's full size counterpart! Maybe he should add brick arches to his list.

i agree that the calculations from first principles for staying of flat surfaces is indeed complicated. There are empirical rules of thumb and simplified formulae available and indeed tabulated 'standards'. The figures for fos quoted In the linked spreadsheet on a similar recent thread for the stayed surfaces of up to 70 indicate (if the underlying calculations are correct) just how conservative the solutions adopted in miniatures for stayed surfaces are when compared to quoted fos of around 3 on the circular barrel. The key for stay pitch is the resistance to deformation of what is effectively a constrained plate where due to the pressure one side is in tension and the other in compression and where the stress in the plate is sufficient to generate plastic deformation. SOD's reference to FEA in CAD would certainly save a lot of manual number crunching!

Paul.

I would say they are the same without getting the books out but I am sure someone will be along to disagree lol.

Paul.

Edited By Paul Kemp on 22/01/2021 01:31:52

I started typing a contribution yesterday but this dumb site logged me out in the process so I lost it and then lost interest.

For Andrew you should ask your inspector for the specific calculations he requires - as he asked he must know? I suspect he has asked due to the requirement in the test code which is fair enough but you could then ask him against what standard he will be assessing the results? Assuming he is competent to assess the results then he should also be capable of doing the numbers, do maybe ask him if he wouldn't mind doing them for you?

There seems to be an assumption that for the published designs calculations have been done? Has anyone seen the supporting calculations for these designs? In fact do any of the published drawings bear any evidence they have been assed or approved by a notified body or in fact any body outside the publisher?

Jason, I don't have that particular book, any chance you could pm me the formula therein for stay spacing? I used to have one from the Indian regulations of all places that seemed to give sensible results for larger scale miniature boilers but I have lost it and the web site I nicked it from has been deleted!

I don't disagree with the comments regarding the Australian code but not convinced we just need a direct copy as it is restrictive on working pressure for steel boilers and I understand prohibits some of the established boilers in use here with proven safety records such as the Simplex design.

SOD, 2 X wp and 1.5 X wp tests are industry standard derived from stress fos.

Paul.

Bazyle,

I would be very happy to see your formula from first principles to provide the pitch of stays. Agreed most of the shell calculations and size v number of stays is pretty basic but I think the calculation to prove resistance to quilting between stays of a flat plate is more complicated?

Paul.

I don't think many decent sized marine steam engines had flywheels, instead they relied on the inertia in the shafting and prop and were flange drive. All the large marine diesels I have worked on have had flange mounted flywheels, no keys just fitted bolts and high torque.

If a flywheel were fitted to a small marine steam engine I would expect it would be secured with a taper gib head key. That's how traction engine flywheels and line shaft pulleys etc were retained, having had to remove some I can vouch for how tight they can hang on! Either that or mounted on a taper on the end of the crank in the same manner shaft couplings are (both with and without keys) the modern type of taper coupling using oil injection to seat and remove are a thing to behold, they can come off with a significant bang and not something you want to be messing with without some restraint in place.

Paul.

Andrew,

Gauge for loco's (larger scale anyway) is generally the distance between the rails, common sizes are 2 1/2", 3 1/2", 5" and 7 1/4"

Traction engines generally are scaled by 1" to foot so 1" scale is 1/12 full size, 1 1/2" is 1/8 full size, 2" is 1/6 full size, 3" is 1/4 full size, 4" is 1/3 full size, 6" is half!

Unfortunately the size of the model is not always a good guide to scale as with railway loco's narrow gauge prototypes are common and a 2" scale ploughing engine will be close to the same overall dimensions as a 4" scale small steam tractor!

If you want to steam any of them you will need a boiler test to get insurance to run them in public. Even if you want to use them in private it's a good idea to at least do your own pressure test before lighting up! Check any paperwork your dad may have had, it may be they have been previously tested which will make re test easier!

Paul.

I had a similar fault develop on the ML7 after turning a lot of cast iron. It has the I assume original Brook Compton motor with air vents and it sucked in a load of cast iron dust which accumulated in the terminal box. Opened it up, blew it out, problem solved.

Paul.

Sorry incorrect, all female BSP threads are not parallel, they may also be tapered. You may use a tapered male thread in either a parallel female or tapered female thread these are accepted as sealing on the thread with an accepted compound. Parallel male threads are not considered as sealing on the thread and should not be used with tapered female threads and as correctly stated are sealed with a conforming washer.

Paul.

Treat it as 3.5" between the rail heads on the straight, depending on the radius curves you might be thinking of using then you might want to consider gauge widening of the track on the curves, the amount depends on the wheel base of the loco's you are intending to run. For example a short wheelbase 040 would probably cope with an 8' radius in 3.5" but a 6 coupled might need the gauge pushing out by up to 1/8" if you want it to go round the corner! For example a 6 coupled 5" gauge loco won't go round much less than a 30' radius curve without slight gauge widening. The back to back dimensions of your wheel sets will also govern points and check rails. Best to go with a standard, there are a few around certainly for 5" gauge, if you can't find one for 3.5" then you can scale it within reason.

Paul.

Spot on I suspect, I am sure to become a shopping partner all you would need to do is cough up. Is there any past partners that were 'struck off' for quality issues or negative feed back on the site?

Never had much luck with my 5" gauge modified Speedy feeding both cylinders from a single lubricator. Solution was a tank divided in two with a pump in each half. I can now monitor easilly both cylinders are getting oil in roughly the same amounts. I don't see why you couldn't make a three element lubricator in a single divided box? Would give confidence and peace of mind!

Paul.

Small wonder "I conveniently missed it" as your elaboration that battery refurbishment is available now didn't appear to be specifically mentioned in the original quote and the point being made by the previous poster was not the potential of being able to get a replacement or even a refurbished battery - but the cost.

"Look at this video. But do remember that battery repairs/replacement/improvement/prices/etc will change as BEVs become more widespread."

In fact "battery" recycling by the likes of Corvus is well underway already outside the automotive industry where batteries are refurbished by replacing defective cells and the refurbished units re-deployed to less arduous duty cycles than their first application - good business for them as they essentially get to sell the same 'battery' twice!

Something you appear to be missing when you are telling all to "get used to it" is the majority of responses on this thread acknowledge change is coming but are highlighting the challenges that need to be overcome in the next 10 to 15 years. Given the infrastructure changes required to support battery electric vehicles I can't fully agree with your statement "nearly all cars will be electric in about 30 years time". I can agree the method of turning the wheels may well be electric motors but in my opinion they will be mainly supported by hydrogen fuel cells and not batteries. Better power density and volume density (dependant on compression) than batteries, more convenient and most similar in refuelling as vehicles are today, less down time for refuelling but more importantly less infrastructure investment required at distribution level. Lastly to return to SOD's energy storage issue is energy is more easilly stored in a gas than as electrons in a battery and it doesn't involve child labour in mining to do it.

Paul.