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Member postings for Clive Foster

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

Thread: Band saw arm weight
01/05/2022 09:43:15
Posted by Hopper on 01/05/2022 00:18:12:
But wouldn't a hydraulic damper system still need adjusting each time to suit the job in hand? Cutting a piece of 4" x 1" flat bar will need less damping than cutting a piece of 2" square tube with 1/16" wall thickness, won't it?

But if the larger machines have a damper as standard, it might be easier to adapt one of those to the smaller machines than using motorbike dampers, which are usually a bit pricey too.

The shop made versions all seem to have some sort of valve for adjustment. In principle it would seem no great problem to arrange a divided dial and calibrate the set up. Hang a chart nearby or stick a label on the machine to give the setting for different materials and size. If you needed more than one turn then copying the Bridgeport quill downfeed scale system with a ruler alongside calibrated in one turn units would not be too difficult.

However its not exactly super critical. Folk like us won't notice the difference between dead nuts right and close enough to work well. I seem to recall one of the home brew versions having a needle valve with 4 turns of useful movement "graduated" in half turns as being close enough.

The motorcycle steering damper folk can just count clicks on the adjuster. The common 70 mm stroke, 330 mm long ones from "China Inc" in various brands and colours are around £30 - £40 which isn't stupid expensive. Ohlins et al are priced for the racer boys so not appropriate. My experience of high end Ohlins, Japanese factory and cheapy import from 30 odd years back was that they were all equally poor at their proper job on a bike but all had similar damping abilities against simple movement.

Depends on the damper design too. There are types with a very savage velocity / force curve giving little variation in movement speed over a wide range of applied forces. So the arm drop won't be too fast on thin materials but for thicker stuff the extra resistance to cutting slows things down enough that the downforce per tooth is still reasonable.

Clive

30/04/2022 17:05:02

Getting back to the original question there seems little doubt that the best solution is an adjustable hydraulic damper set-up allowing the rate of fall to be set to obtain a suitable cutting pressure on the blade.

Various designs have been published over the years.

I imagine an old car suspension damper might be a good source for many of the components. Unfortunately I'm not aware of a source for how to modify the piston to give the requisite flow to control of down-feed and full flow when lifting back into position.

Its reported than a motorcycle steering damper of the adjustable type can be made to work well.

May be relevant to note that the larger version has hydraulic downfeed control and is generally considered a workmanlike device that "just works".

Fundamentally the spring system is flawed engineering but better than nothing. Its primary virtue being low cost. Essential in a device that has to hit a relatively low price point. Big brother is over double the cost. The effetcive hydraulic downfeed control doublets being a significant contributor to the difference.

Clive

Thread: Need advice on clearing Dads shed
27/04/2022 19:50:32

Theoretically you get maybe 3 or 4 times as much money if you break up and sell the contents on E-Bay / Gumtree / FB Marketplace / local ad-paper rather than call the clearance man. But its a boat load of work even if you know exactly what you have. Takes patience to get best prices too.

Selling as one to a private purchaser is unlikely. Too much there and, frankly, too much value for the pockets of someone starting out with very little to afford.

Lord knows what a fair value for that Tri-Leva Myford with the add on electric feed drive kit is. Heard of those kits but never seen one.

Clive

Edited By Clive Foster on 27/04/2022 20:02:56

Thread: Alternative Ways of Retaining Shafts
26/04/2022 17:52:42
Posted by KWIL on 26/04/2022 15:47:14:

Clive.

Nozzle made of PTFE will not melt, nylon does.

Yep.

Noticed that!

Which is why I reckoned it was nylon or something similar. My own is much less melt prone.

I guess thats why there were several extra nozzles in the box. Its what stores issued when I drew mine. Still had a spare or two when the spring died after two or three decades. But then I was lab rat not electronics guru so circuit work was occasional not the daily grind.

Clive

26/04/2022 15:30:27

The one I had at work used a large headed screw running into a tapped hole in the end of the rod. Spring pressed on the screw which also held the piston, made some sort of not quite hard plastic so it acted as a buffer for the end of travel stop. Spring was only just long enough so it ran out of force about when piston got to the end.

As usual the (nylon) nozzle unit unscrewed so the removed solder could be shaken out of the tube and wiped off the spring. Having virtually no spring pressure left at end of travel made it easier to get the nozzle on without cross threading. The (cheapy) I got for home use has agood dela or residual pressure so the nozzle has to be pushed quite hard to engage the thread.

Having the spring pressure taken by the screw head that also holds the piston means the operating rod is pretty much just along for the ride minimising any force on the threads. Don't see any reason for the piston to be a super fit in the barrel so simply screwing (with loctite?) the piston onto the rod should do fine.

Clive

Thread: Electromagnetic Wave Interference
17/04/2022 16:24:37

Joseph

Good points with which I entirely agree with for a VFD box bought as a stand alone unit for customer installation.

However Newton Tesla supply the motor, inverter and pendant as a complete kit with all wiring save for the power input to the VFD. As such the EMC issues should have been dealt with as bought and no problems ought to occur so long as the VFD to motor wiring isn't modified or, if not already pre-wired, not installed as per the instructions.

If the controls are on a separate pendant it would seem to take some seriously misguided creativity to get the VFD and its output wiring close enough a reasonably made DRO box for it to be affected by radiated EMC.

Obviously given the price / performance limitations of anything sold on the consumer market there will be edge cases where ambient sensitivity to EMC may be such that a normally acceptably low level of emissions may still be too high making extra filtration and installation precautions needful.

Lathe plus DRO is pretty much standard these days for anyone whose pockets are deep enough to buy an off the shelf motor and VFD kit. So it should just work.

Newton Tesla have earned a decent reputation for supplying workmanlike equipment so it sounds as if something is seriously wrong.

SOD

Having had some experience with sorting EMC issues back in the days when it first became a thing it really isn't something where individual experimentation beyond simple cook book add ons is likely to be rewarding. Bottom line is that the rules for decently well behaved equipment design are now well established as are those for proper installation.

A kit of decent quality equipment from a reputable supplier should  "just work" unless there is something seriously odd going on or if you want to use it for duties its not made for. This is a bread and butter product for Newton Tesla and the expectation is that any EMC issues will be minor and associated with something unduly sensitive. Modern DROs should cope with any emissions from a reasonably positioned VFD just fine.

Clive

Edited By Clive Foster on 17/04/2022 16:36:20

17/04/2022 15:04:52

Howard

Not your problem.

Contact Newton Tesla about sending it back as not fit for purpose / defective.

Whole point of buying a full motor and inverter kit is that its properly engineered and just works.

At the very least I'd expect Newton Tesla to say "Ooops, shouldn't happen. Try the enclosed filter. If it works please pay £ ---.". As the instructions admit to a potential problem they should, subject to supply chain issues, have the filters in stock.

Obviously at consumer prices the ultimate in EMC protection cannot be provided but getting a workmanlike and legal system goes with the territory. I would have expected Newton Tesla to have performed basic EMC tests on the assembly as a matter of course with some documentation indicating what to expect if installed as advised without messing around with the wiring.

That level of EMC noise is just plain wrong and I suspect the inverter is defective in some way. Mitsubishi have a well deserved reputation for decent engineering. Certainly the two older ones I have show no EMC issues despite very basic installation.

Clive

Thread: Redundancy, electrical
17/04/2022 09:08:23
Posted by Peter Greene 🇨🇦 on 17/04/2022 01:55:21:

My iPhone-6 is about to become obsolete.

Define obsolete.

Despite not getting iOS updates it will still do just fine as a phone, E-Mail, camera, music player et al.

Won't bite until things like internet banking, booking services and similar that need live interaction with specialised software stop supporting that operating system. Which generally seems to be security issues. My old iPhone 4S still runs fine and would do phone calls, E-Mail et "other simple stuff" al but got swopped for a first generation SE when Barclays pulled support for internet banking. Now relegated to calculator and othe workshop applications duties.

I'd be unsurprised to discover that something like an iPhone 6 could be kept running for a decade beyond end of production if you didn't need to interact with secure services.

Its a question of when technology and interconnection methods stabilise. Once stable the old stuff just keeps on trucking.

(Writing this on a mid-2010 Macbook Pro 17" running OS 10.12.6 which does everything just fine. Not upgrading 'cos I'd need to spend £1,000 to upgrade VectorWorks for the new OS and get precisely nowt for it because the CAD side hasn't been touched for yeras.)

Clive

Thread: Before calculators
16/04/2022 11:33:27
Posted by John Doe 2 on 16/04/2022 10:35:45:
But how do you do it without a measuring device of any sort?

Basically pins and string or equivalent.

Divide by 2 is easy. Fix one end of the string, find the length to the other side and double back to the original end. Loop back position gives you half.

Repeat as needed for all the even divisions.

For thirds you set the string in a right angled triangle with the long side 1 1/2 units long. Without measuring equipment best way is probably to set up a rectangle of with one pair of sides one unit long and the diagonals 1 1/2 long. Equal diagonals give right angled corners as close as you care to go.

Same trick for all the other prime divisions.

Tedious but not hard.

Makes you realise why common units (imperial for us) wer always done by dividinng down from something sensible.

Clive

Thread: DRO readouts freezing when adding second scale
10/04/2022 14:01:27

Sounds like a power supply issue. Enough power to drive one readout properly but when the second one is added it can't supply either the voltage or current needed to run both.

As the scales work OK individually at least we can rule out socket pin out incompatibility. Unfortunately not all the 9 pin D connectors have the same layout.

Clive

Thread: Vice - again
07/04/2022 11:47:43

John

That's a much more secure and engineering way of going about things.

Putting a set of extra high jaws in the box with the vice to be used like that, and occasionally in the normal position, seems to me better than suggesting using the tiny lips left when the standard jaw is utilised. Maybe add tapped holes in the top of the fixed jaw too so the standard jaws could be set flat giving a reasonably substantial lip too. Such holes would also let you add clamps to either hold work to the top of the vice or provide extra retention to a component which is difficult to hold securely by simple clamping. I've had jobs shift for lack of that extra top clamp.

Things that I might well have done to my vices if the basic casting were more suitable.

The common way is more of a "looks nice in the specifications" thing rather than "really useful for all sorts of difficult stuff". But throwing in tall jaws et al puts the price up without the gains being immediately obvious to the ordinary purchaser. That said I'd have thought that Arc Euros reputation for quality could stand the extra few pounds for two more tapped holes and taller jaws to use on the back and front.

My experience suggests that the 4" size would gain most from readily available, adequately secure, extra capacity given by tall jaws used as shown in Johns pictures. I see a fair number of jobs that wouldn't fit the standard opening of a 4" Versatile but would do just fine with Johns taller jaws on back and front.

With my VJ400 ones I, of course, just pull the pin and shift the nut for extra opening beyond a normal 4" vice capacity. But thats why I bought them after all. Removing the standard jaws and fitting taller jaws back and front on a Versatile would be nearly as easy. Beats the heck out of pulling the vice and the "how do I strap this to the table" headache for sure. Let alone tramming the vice in when you put it back.

Clive

06/04/2022 19:12:01

Colin

I'm impressed by the capacity / weight ratio of that ARC 125 mm Versatile. At 22 kg its actually a bit lighter than the Vertex VJ400, which is said to be just under 25 kg, so its respectably handleable.

According to Google Andrews Kurt tips the scales at nearly 38 kg, a couple or three kg heavier than my 6" Abwood so shifting is very much workout time.

If they had been around at that relative price I might well have bought ARC Versatiles instead of my Vertexes as, for me at least, the useful capacity would have been similar.

I'm unconvinced as to the utility of the extra jaw positions as the work holding is fundamentally via a small lip which seems less secure than one would ideally like. Although willing to be convinced to the contrary by photographic evidence I'm not sure I'd have the nerve to actually try.

If I were buy another vice it would be a Chick! Not likely to actually happen. At around £2,000 a pop they cost more than I, and most other folk pay for their mills. But I am eying up the practicality of a look-alike as part of a project that needs an integrated vice.

Clive

Thread: Connection to compressor
06/04/2022 13:17:43

+1 for the 6 mm push fit system. inexpensive, the ordinary blue'n black plastic fittings will do fine but the metal ones are swankier and cost little more. Fittings can be found for just about any reasonable thread for such applications.

Easy to use and designed for the job. Just make sure you cut the tube straight with a really sharp cutter whilst supporting the tube bore to ensure you don't deform it. Hanging burrs can upset the sealing O ring(s) inside.

I've always used nylon tube which was what the system was first designed to use. A bit on the stiff side for feeding round tighter bends but totally reliable and well up to the job. My 22 year old Range Rover P38 air suspension is still on the original factory fit nylon 6 mm tube and push fit connections with nary a leak at (nominal) 160 psi. So I guess the stuff works.

Not sure about Jasons reference to PVC tube. Usual alternative to nylon is polythene (PU). Various types. All more flexible, usually more expensive and all less durable than nylon in hostile environments. Not that any normal person would notice the differences.

Clive

Thread: Vice - again
06/04/2022 09:43:19

Colin

Cheaping out on a vice, especially your first one, is always a bad move. Although its generally pretty easy to re-work one of essentially sound design and construction with inaccuracies due to a selling price too low for the factory to afford proper quality control its a faff you can do without when you just want to use the mill.

Going to Arc is a good move to get a decent product a fair price.

However I'd question the advice to get a 6" one for home shop use on a Bridgeport. In practice the main advantage of a 6" vice over a 4" one is jaw opening. The disadvantage is its big and 'kin heavy. I "obtained" a 6" Abwood for my Bridgeport which, after refurb is probably better than any of the affordable new options, and have used it maybe twice in 20 years. However the price was right, basically negative as part of a complex deal.

My go to vices are a pair of Vertex VJ400 110 mm jaw width / 180 mm max opening purchased from Rotagrip on a show offer when I had my big square column bench mill.

vertex vj 400 vice r.jpg

I'm convinced Rotagrip cocked up the show pricing but my credit card came out smoking and I've never regretted it.

Basically an economy version of a hydraulic vice with screw drive. Actual screw driven closing range is about 2 1/2 inches but the nut is located by a simple pull out pin with three alternate positions for openings of just under 2 1/2, 5, and 7 1/4 inches. Specification accuracy is 0.01 mm / 100 mm, mine came out better when I checked them but the figures are long lost.

Currently £325 from Rotagrip **LINK**

http://www.rotagriponline.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=19436&category_id=125&option=com_virtuemart&Itemid=29

Which still seems pretty good value. The hydraulic version is £300 more!

I keep the 3" vice in the background for use on angle plates and sine tables.

In defiance of popular opinion I keep the swivel base on.

A Bridgeport has ample room under the quill and keeping the swivel makes it easy to set the jaws parallel to the slots for normal use. I find that, once set, simply pulling back against the locating bolts before final tightening is repeatable to a thou or so in 4". Good enough for most jobs. Generally the bolt down slots on a vice aren't super accurate in position so you need to either accept the need to a djust each time you fit it or do a bt of re-working. Jason reports that his Arc supplied vice was pretty much dead nuts on as delivered. I reckon he was either lucky or Ketan sorted out a special one for his mate! From what I've seen something in the region of 5 to 10 thou error across 4" in jaw allignment when using simple pull back is more typical. Not bad given that the slots are rarely fully machined.

Clive

Edited By Clive Foster on 06/04/2022 09:45:06

Thread: What size are my nipples
03/04/2022 18:58:39
Posted by Tim Stevens on 03/04/2022 18:14:51:

The answer, as usual, is 'it all depends'.

..........

The main clue, I suggest, for grease nipples is the size of the relevant spanner.

......

Cheers, Tim

Spanner sizes?

Measured across flats in ascending order

M6................0.394"........................10.00 mm

0 BA.............0.413"........................10.50 mm

1/4" UNF.......0.438".........7/16".......11.11 mm

1/4" BSF.......0.525"........................13.34 mm

(assuming the spreadsheet I found ages ago is right)

Of course grease and oil nipples often use undersize hexagons.

BSF marginally more likely on a Pultra think.

Clive

Edited By Clive Foster on 03/04/2022 18:59:24

03/04/2022 16:02:55

0 BA and 1/4" BSF are dangerously close in size and pitch. 14 thou difference in outside diameter, 12 thou in core diameter, 0.38 tpi difference in pitch. 0 BA being smaller and finer.

Depending on the tolerances involved both will screw onto the other with varying degrees of ease and slack. Despite the difference in thread form. Such mis-fits dangerously reduce the ultimate tensile strength of the joint so pull out stresses will be much lower, probably around 1/4 of a properly mated pair.

Clive

Thread: Holding taps in a drill press
03/04/2022 10:38:40

+1 for serial taps.

Considerable reduction in tapping force which makes life much less fraught with small taps. Especially on difficult materials.

Yesterday I used my M4 serial set when making some 6 mm long threaded inserts to glue into thick glass fibre panels without decent rear access for proper headed inserts. M6 stainless steel stubs tapped M4. Done on the S&B 1024 lathe by holding the tap in a chuck in the tailstock with the stub gripped a collet in the spindle. Lathe in neutral. Spindle turned by hand using the collet handwheel. Bit of push in on the tailstock to engage the tap.

Easy to feel the difference between ordinary hand tap, spiral form machine tap and serial ones. As the collet was gripping on a short thread holding force wasn't wonderful but both ordinary taps and the machine tap would turn the stub when well into the thread. Accompanied by "cracking" feel. Not good for the nerves. Plenty of trefolux tapping lube applied of coarse. Fairly hefty lathe so plenty of metal turning round with a good deal of inertia to watch out for.

These days I buy serial or machine taps if I have the choice.

One issue to bear in mind when tapping in a drill chuck is the drag and inertia of the spindle, belt and motor. Which interferes with feel, dangerously so on small taps. Best to drop the belt or at least put it on top speed so the motor is effectively geared down relative to the spindle reducing its contribution to the load.

When using smaller taps there is much to be said in favour of the sliding tap holder on a spigot devices with a knurled wheel to turn by hand. No load from the drill spindle so far easier to feel what's happening so you can stop and reverse before the tap breaks. Something I should have made many years ago but no longer need as I have alternatives.

Clive

Edited By Clive Foster on 03/04/2022 10:40:21

Thread: M 1.4 threaded steel rod
02/04/2022 15:05:47

Bernard

Very probably knurling would do fine but probably even harder to arrange than threads on that diameter.

Clive

02/04/2022 10:42:59

Gary

Nice to know that such things go quite easily given reasonable care.

Clive

02/04/2022 10:15:42

pgk pgk

Thanks for that. Looks like I do have an option for correct size to thread roll then.

1.5 mm fully threaded would be too large. Specific thread isn't important, its the grooves that matter as they help it hold in place.

Clive

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