Member postings for Clive Foster

Grindstone Cowboy

Cordless drill keyless chucks aren't suitable for machine tools as they don't have the grip tighter under pressure capability. On the other hand they don't almost immediately loosen when pressure is removed.

Proper machine tool keyless chucks tighten up quite seriously under pressure which helps prevent drills spinning. The release tendency when pressure is removed helps undoing to get the drill out.

Never bottom out a drill in a good quality keyless chuck. The drill has to have bit of room to move back to drive the self tightening. If an Albrecht or similar bottoms out it's the very devil to undo. Hex shanks, like those on hole saw arbors tend to slip back with similar jam up results.

Clive

Edited By Clive Foster on 11/03/2023 12:40:02

DC31k

Sorry missed your post earlier.

The march of time and technological advancement makes very little difference here as we are dealing with fundamental motor physics.

The issue is how big are the storage capacitors and how much energy is available to run the motor up. Even with soft start there is no getting around the fact that a motor is near as dammit a dead short when turned on. It needs a certain current flow and voltage to get it moving. If too much energy is sucked out of the capacitors too quickly the applied voltage falls too low before the moron gets moving and it cannot start. Just sits there and buzzes. Basically acting as a seriously weird transformer.

My big tome on motors has whole chapters devoted to calculating the immediate inrush current and design methods to control it so that a motor will reliably start under load without upsetting the local supply. Very important if running off a generator. Star-Delta switching and avoiding multi-speed motors being the easy beginning before the maths goes to eye-watering, brain leaking out of your ears level. 1970's book so it assumes algebra, slide rule and mechanical calculator level calculation.

The VFD Rich has is clearly undersize in the storage capacitor department when it comes to meeting the inrush current on the high speed setting. Only having 380 volts doesn't help as, obviously, the lower voltage reduces the energy the capacitors can store. Which may well be enough to make the difference between not quite and just enough.

Large capacitors are expensive.

As ever with economy range you have to expect usually good enough engineering and specifications. Which is excellent until it isn't.

Buying a higher power unit basically gets you bigger capacitors and more oomph to get things going.

It's annoying that, apparently, no-one makes professional level versions of these step up VFD boxes where there are no hidden performance issues. You'd have thought there would be a big market in America as an alternative to expensive Phase Perfect boxes and the like.

In the previously mentioned Holbrook application the motor only drives the gearbox on start up so the load was not be great. But the inrush current is still very, very high. With my Smart and Brown the modified VFD just ran out of volts at high speed. The capacitors were clearly adequately sized as the machine started OK. In standard trim running 440 volts that VFD would have had no problems.

Clive

Chris

When this subject came up before there were pictures of a clamp tool with very stubby arms splayed out at what I recall as looking like about 45°.It was said to work reliably. Possibly that was the one Neil Wyatt used.

The common affordable commercial ones have relatively long arms running parallel to each other off a vertical pivot carrier with a bolt in between to do the clamping. The distances involved multiply any deflection tendencies due to bearing play or less than optimal arm stiffness. My Marlco is built like the proverbial tank and still isn't completely stiff.

The fundamental problem with inadequate stiffness is that it becomes difficult to immediately force the tool into a starting a clean single knurl. Any flex lets it spring so it effectively bounces starting a second or even third knurl pattern. Once started the knurls follow this multiple pattern, speeding up an down a touch as required.

I have gotten this effect with the Marlco but that has an external lever to apply pressure to control the knurling process. Quickly leaning seriously on that lever can generate enough pressure to force things into proper single pattern knurling. Usually! I can't see that sort of thing being possible with the type having long arms with a clamping screw between them. You can't get the extra pressure on fast enough to force the system onto one pattern.

With the hand squeezed nutcracker type slightly reducing the squeeze pressure followed by hard re-application generally forces a double or triple knurl into a single pattern.

Free spinning knurls are important. I had one reduce itself to a D shape on the Marlco because it was a bit stiff. My fault. Should have checked it over properly before putting into service. But it seemed OK and I had a job to do the day after I bought it home. That said I suspect the knurls it came with were economy range and less hard than ideal.

Clive.

Thats a double or triple pattern with only one knurl doing any work.

Things to check :-

Is the material suitable? Anything that has work hardening tendencies will be hard to knurl at home. In general stainless steels can only be reliably and satisfactorily knurled using the cut knurling system.

Are the knurls sharp?

Do the knurls spin freely under load?

Is your knurling tool strong enough to apply enough force to the job and rigid enough to keep the knurls correctly aligned?

Is your knurling tool set up properly to pinch on the centre line of the job with the knurls aligned with the lathe axis?

The sample looks as if the knurls are out of line with the lathe axis and the tool is sufficiently flexible to let the ineffective knurl skid sideways.

Knurling using conventional push knurls is pretty brutal process. Considerable force and rigid tooling is needed if things are to just work. I have a hefty Marlco clamp knurler and ex-industrial machines. Even then the process is not always routine. It's very important tha the forces between the knurls are balanced. If I have issues its generally because I've gotten rush headed and not set things up balanced.

Although plenty of people have gotten good results from clamp and even push knurling on smaller machines my view is that the three wheel, hand squeezed "nutcracker" type is far more reliable on smaller lathes. Being hand operated you can feel whats going on. Its obvious when things aren't going well.

Here is picture of mine.

Bought when I was driving SouthBend 9" it instantly solved my knurling woes. The 9" Southbend is sturdy enough to make a decent stab at clamp knurling with a lighter weight tool or even push knurling but it always took a bit of experimenting to get good results. Even then there were failures where the job just point blank refused.

It's noticeable that people who report good results with clamp knurling on smaller machines, our esteemed MEW editor for one, tend to use tools with short stiff arms. Commercial variants all seem to have the arms too far apart and too long for optimum stiffness. Once you can get a knurl started and flowing the process goes well. Its the initial getting going where any limitations of stiffness show up.

Clive

PS Am I correct in recalling that you have a Pultra? Although this is one of the sturdiest of the very small machines, knurling is really expecting a boy to do a mans work. Precise technique and excellent tooling will be essential.

Edited By Clive Foster on 10/03/2023 19:26:51

John P

Martins method of directly driving a rotary table, spin-dexer or simple spindle seems much more appropriate than attempting to drive a dividing head via its normal worm and wheel.

Direct 1:1 drive will replicate the feedscrew pitch.

Coarser pitches will need the rotary drive stepped down in the same ratio as the feedscrew and desired pitch. So, for example, if the feedscrew is 8 tip and the desired pitch 1" then 8:1 step down will do the deed. It's unlikely that any ratio be large enough to be wildly impractical. Its the method I shall adopt should I ever need to do "figure 8" oiling grooves.

Admittedly producing a metric pitch on an imperial machine or imperial pitch on a metric machine will be tricky as the conversion gear(s) need to be arranged. Arranging temporary metric or imperial feedscrew using decent studding might be more attractive in that case. As Y-axis feed will not be needed once all is set up an external screw is feasible with the nut clamped to the Y dovetails.

Clive

Martin

Cunning set up. Driving the rotary table directly via a chain of gears was, for me, a classic "D'oh obvious" now someone has shown me thing. Would work just as well with a spindexer too.

Brilliant lateral thinking.

Many professional dividing heads, like my Cincinnati copy Edgewick have a drive shaft provided for this sort of use. Cincinnati had whole bolt on change wheel bracket, gear set and cover assembly to use their heads on their mills. My dividing head came with couple of chain and sprocket assemblies that were used to connect it to a Bridgeport for, as I recall it, some sort of mould making work.

Clive

John

I'm impressed that a Morse Taper works so well at holding a die head.

Like most folk using older machines I've had too many issues with drills pulling out of, presumably, less than perfect tapers to be totally confident in their holding power against pull out forces.

Not quite the same but even after recutting the socket the MT 3 on my big Pollard drill isn't totally reliable when holding Pollard tapping heads. Which admittedly are quite large and quite heavy. Lifting the drill down-feed handle to engage auto reverse occasionally drops the taper either immediately or part way back.

Hence my skepticism as to whether the mutual grip of an old shank in an old socket will suffice. My first encounters with a brand new shank in brand new taper were somewhat educational. The difference between old, albeit still adequately functional when used with care, and new being profound.

Clive

I'm unconvinced as to the general suitability of MT taper for mounting a Coventry Die Head. By their very nature there is significant lengthways pulling force on the head as it cuts the thread which will tend to pull it out of the MT socket.

When using one with an MT taper in a tailstock the tailstock has to be fed hard enough to keep it properly seated in the taper but not so hard as to interfere with the thread profile. When reaching the end of the thread the taper seating grip has to be sufficient to resist the spring forces as the head pulls forward to trigger the opening process. If the taper grip is inadequate the head will go round with the job rather than continue cutting the thread. A bit fraught methinks.

If the tapers are less than perfect it would seem that the only safe way is to eschew the self opening feature and use it like a simple fixed tailstock die carrier keeping continuous feed force applied and stopping the lathe when you get to the end of the thread. The head can then be opened manually. Perfectly practical unless the tapers are distressed almost to the point of being unusable but it does loose most of the benefits. Frankly an ordinary sliding die holder is may then be easier, although they too will spin if the tapers are poor.

My die head has a parallel shank so I made a simple holder to mount it in a Dickson QC tool holder by welding a split tube to a solid bar. I feed up to a bed stop using the saddle hand wheel whereupon the thread pulls the head forward to trigger the disengagement. The disengagement pull forward distance is significant. Power feed by setting up the appropriate pitch and driving as per screw cutting works well but the half nuts need to be dropped promptly and final feed to the stop done by hand.

I trimmed the bar to match the tube radius on the lathe with it mounted in the toolpost to ensure all was aligned. Did the same to finish the bore. The portion behind the die head shank is bored little larger so I can easily set it on centre using a short cylinder gauge mounted in the tailstock taper.

It lives permanently in that toolholder, carefully selected as being the grottiest one which I didn't mind loosing from general stock.

Clive

Deleted

Edited By Clive Foster on 05/03/2023 12:32:40

Trouble with rust is it expands taking up more room than the original metal.

Plus Gas Formula A is said to reduce the volume of rust reducing jamming effects.

Given time to penetrate it appears to work. Regular squirting with an aerosol over a week or two interspersed with careful knocking as advised above may be effective. Might help if you can support it so gravity acts to pull the main casting off, its quite heavy.

That method shifted a well jammed turret ram on a Bridgeport for me. Removed the ram and set it up pointing down at an angle, anointed the joint with plus gas and knocked it with a dead blow 3 times a day, reversed it every 3 or 4 days. After about 3 weeks I went to give it its morning anointing and found the turret and slid down all on its ownsome overnight.

Clive

Back in my SouthBend driving days I made a number of 4 way toolposts from standard stock sections. Don't recall the exact details but I think 1/4" or 3/8" steel plate for the base, 1/2" plate for the top and, probably, 1" or 1 1/4" alloy bar for the middle. Screwed and glued together using either M5 or M6 countersunk hex socket screws and one of the Loctite construction adhesives.

Design was fundamentally based on what I had or could scrounge. Alloy is plenty strong enough fro the centre part and far easier to tap. My then boss called me several rude names prefixed with "cheating ..." as he'd recently carved two from solid for his Boxford. Which seemed far too much like hard work to me.

Don't leave the base flat. Put a shallow recess of diameter around half the block width in the centre. This ensures altho the hold down force is applied to the outside of the block where it has much more mechanical advantage against twisting. A flat base is likely to mostly hold close to the middle so needs to be held harder ton stop twist. A "gasket" of thin card or soft aluminium spreads the load and improves grip. Need to change a card gasket every year as it picks up oil.

Were I to make more I'd do two slot blocks rather than four ways. Four way ones have undesirable porcupine tendencies and, in my experience loading more than two tools tends to be inconvenient. If you intend to use interchangeable tip carbide tools set the base thickness so you don't need shims.

Clive

Very true but you have to be reasonable as to how large a step there is between what a beginner already knows how to do and what they need to learn for the next job. Too big a step or too many steps leads to, at best, disillusionment with unattractive results and all too often compete failure. Too much of that and a new hobby will be sought.

Unnecessary multiplication of complication, whether in design, construction or work holding should be avoided wherever possible. Which goes in spades for novice projects. That half circle part is tricky problem in work holding that has no place in a project intended for the inexperienced. There are so many ways it can go wrong. Certainly way too much trouble for pure cosmetics.

I would obtain a piece of 5/8 x 5/16 flat bar and reduce it to whatever shape seems pleasing. Whether using a longer piece and turning it half circle as suggested in my previous post, filing the corners taper or simply radiusing the edges. Option 3 for me!

With the blank prepared mount it in the four jaw chuck with the flat face hard against at least two jaw stops so the basic slot shape can be produced by drilling a line of holes. You may need a scrap behind the job to keep the drill away from the jaws. The easy way to get the sideways step is to use a scrap of material as a setting gauge. Loosen one of the jaws holding it longways, insert the "gauge", bring the jaw back to lightly touch it, remove the gauge and use the opposite jaw to push the part over so its gripped ready for the next hole. Loosen the short ways jaws a touch so it slides without rocking.

Drill alternate holes so the is a gap between the holes drilled in the first run. Start with a centre drill to give a decent lead in. If the web between the holes is significantly smaller than the drill diameter find something to make decently fitting plugs to help keep the drill true. Brass would be best but alloy, steel or even JB weld will work. As ever with brass the drill needs to be decently sharp.

If you do decide to make it half circle as per plans first file a flat almost as wide as the slot will be so the drill has a nice clean start. Brass is skiddy at the best of times. Starting on a curved surface is an open invitation to trouble. A three flute centre cutting end mill, such as the old Clarkson throw-away series would be better than a drill for producing the the holes. Probably too short to go right through in that size but one will give a nice clean round guide hole most of the way through to finish with a drill.

Clive

Mexico plant could well be due to difficulty of getting appropriately skilled workers in the USA.

Probably supply chain issues too. US firms moving manufacture to Mexico has considerably boosted local supply chain and, correspondingly hollowed out the US one.

Political issues with getting permission to build factories in the US too.

Clive

Further to Hoppers suggestion of using square bar maybe consider rectangular bar.

5/8" x 3/8" can be got at not too silly prices.

If you get a piece maybe an inch longer than you need the half round, or whatever variant shape you find pleasing, can be done in the lathe. Mount in four jaw with the flat on centre and turn down the other side to half round. I'd consider a flat on top the same width as the slot. File off the corners first to reduce the risk of bending during turning and keep the knock-knock-knock noises down.

Doing the most of the work with only short sections sticking out of the chuck would be wise to reduce stresses. Finish with a couple of very fine cuts full length.

Clive

Edited By Clive Foster on 03/03/2023 13:16:09

For a reasonably common current model machine in decent clean condition that can still be got new I agree half new price is reasonable expectation. Possibly a little more.

Bidding wars are for rarities or obsolete machine of high reputation. Generally at well less than half new price as such things tend to have been well beyond a private persons pocket when new.

The big imponderables are transport and loading.

If the machine is only a few miles up the road standing in a clear garage with easy access for the trailer or truck with a couple of fit healthy guys on hand to help load I'd pay a bit over the odds. Saturday morning job!

If I have to drive 400 miles (Manchester maybe?) and dig it out of a cluttered shed with only my mate to help me its going to have to be seriously rare and highly desirable if I'm going to pay a good price. Realistically thats £200 + in fuel, food for me and mate, a very long day and either a decent wodge to my mate or serious favours owed.

Knock £500 off.

I'd give Facebook marketplace and some of the local buy and sell groups a try first before E-Bay. Facebook tends to be much more local and there is less competition. The "Hmm not to far" effect is valid for turning "Maybe I'd like one" int "Stuff it I'll get it". I've occasionally gotten lucky but E-Bay is more relatable.

Clive

Richard

I've been trying to remember how much radiator / heater hose stretched when I used it tyre fashion many years ago. Unfortunately the nearest thing to a useful recollection is that I made the base diameter close to, or perhaps a touch larger than, the ridge formed into the hard connecting pipe to stop the house slipping off once the jubilee or equivalent clip had been done up.

On that basis 3 or 4 mm stretch on your 35 mm ID hose doesn't seem unreasonable. Whether it will hold purely by stretch or whether it will need adhesive I know not.

One of those "tried a number of things" jobs which I was glad to see the back of and fairly resolved not to do again in future if at all possible.

Pushing heater hose in steel tubes with suitable mounts welded on as the basis for stiff hinges and home brew anti vibe efforts was a different matter. Used for a number of things and well up too the top of the "works well" list.

Clive

Way back I asked a Loctite rep at an exhibition what the difference between thread lockers and retainers was. He grinned and said "often it's pretty much just the data sheet"!

In such cases the stuff inside was effectively the same but trying to dual standard the data sheets would have been just too confusing.

But many are distinctly different, largely when it comes to gap filling and installation details.

I made my excuses and left before he really got going!

If you start reading data sheets for retainers, best practice for installation to get good results and what happens if best practice isn't followed it doesn't take long before your brain overload safety kicks in. For an awful lot of Loctite products there are quite a few ways of getting very similar ultimate strengths. But the installation conditions to get the best can vary widely.

Clive

£160 is indeed outrageous for a 6 mm Timesert kit that can be got for around $90 in the USA.

Found an Amazon listing at £133 but you'd need to get the longer inserts on top as that only has the standard shorter ones. Another £30!

There is an apparent Timesert clone branded Sennmonn which are also one piece with rim and proper thread lead in. Around £80 on Amazon for M6 x 1 kit. Stainless steel inserts make them attractive but they are simple bushes which, unlike Timeserts, aren't expanded into place. Need to use high strength Loctite to retain them which ought to be fine.

Realistically £160 (if you get via Amazon) for a Timesert kit isn't too stupid if it gets you a known good repair that just works. Any sort of welding and other mechanical work to give clean hole for a helical or a filled hole to drill and tap yourself is liable to end up a similar cost. At least if you go the timesert route you have the kit for other jobs. Or, given the known outrageous price, odds are getting around half your money back via E-Bay, Facebook Marketplace et al seem pretty good.

The Sennmonn kit seems a pretty good option as its effectively the same as making your own bushes but you get all the tooling too.

Clive

Edited By Clive Foster on 27/02/2023 16:12:30

A standard M6 Timesert has an 8mm Ø countersunk section at the top going down a couple of mm or so. This will take out the top end of your hole taper and give a clean entry to the screw. There may be a small portion of the insert not completely supported where the taper runs out but that should be no problem.

I've successfully done similar repairs in "abused" holes using Timeserts installed as per book. I used Loctite for additional back up strength but whether that was necessary is a matter of opinion. Worked for me on jobs rather more heavily loaded than your job appears to be too.

There is no doubt that the all one piece bush style construction of a Timesert deals much better with abused holes than the simpler, spring style, helical construction. I'm convinced that the solid ring at the top is a major contributor to this as it ensures a clean entry to the screw or bolt. Pretty much every problem I've seen with helicoiled holes has been due to the screw or bolt not entering cleanly and subsequently being forced.

Bad point about Timeserts is the very high cost. Although I have to wonder if there are quality / performance issues withe the economy range helicoil clone kits which may mean they are best restricted to less ambitious duties.

Clive

Edited By Clive Foster on 27/02/2023 13:42:56

Another satisfied Brother user.

I have the MFC J6930 DW with two paper trays. One for A4 and one for A3. It's a big lump but two trays make life easy.

Had the single A4 predecessor before.

Both have stood up well to rather intermittent use although I suspect almost as much ink goes in the cleaning cycle as on the paper.

Clive