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: Kennedy Hacksaw bearing replacement|
At that sort of power level Poly-Vee belts run just fine on adequately sized flat belt pulleys. Vee side down. Commonly advocated by the SouthBend fraternity. Certainly worked just fine on my Heavy 10 once I'd nailed the belt joining technique.
Motor pulley is small so probably makes more sense to buy one of appropriate size than make one. Although I found making an unobtanium 3/4" diameter one for something electric easy enough using micrometer bed stop to get the groove spacing right. Probably a right pain without a micrometer stop or DRO tho'.
A nooge around the belt suppliers websites should unearth a catalogue with length calculation formulae. I found them very accurate 5 to 10 years back when I had a bunch of Poly-Vee jobs. Certainly better than the usual Vee belt ones. Even so its unlikely that you will find just the right size belt. Either add a spring loaded tensioner device, which will also increase the belt wrap on the motor pulley, or make the motor moveable to set belt tension. The spring tensioner has worked fine for me on various jobs. Basically two cheap ball bearings in a tube for the roller and, usually, a motorcycle stand spring. Or just use a slot and locking bolt to fix the arm.
I'd always understood that the limited belt wrap on the motor pulley was intended to act as a simple power limiter so the saw would stop rather than break the blade if things jammed. The one at work got used a lot for cutting 1" square "speed frame" tube by various unfeeling folk and got jammed on a regular basis once the blade got worn but never, to my recollection, broke blade. Wore out plenty tho'. Never could get the unwashed to understand that when the teeth are more or less gone changing the blade is desirable.
Edited By Clive Foster on 19/08/2019 18:50:10
|Thread: Digital inclinometers|
Basically two types of tilt sensors in these devices.
Old style single axis ones like the Wixey have a pendulum and angle sensor. Tilt it, the pendulum swings and the sensor says how far. Simple, easy to understand and fundamentally accurate but they do need to be well made. You do need to be aware of axis orthogonality issues when making measurements of small angles. If its not directly aligned with the tilt axis funny results are possible. Fundamentally a good technology but, as ever, the consumer variants are "made too cheap". No excuse for the flat battery issue. Electronic variant of the Dumpy and Cowley levels really.
Two axis ones and some more modern single axis ones use MEMS (Micro-Electronic Mechanical System) devices. Silicon chip technology applied to itsy bitsy teensy mechanics. Basically they measure the acceleration due to gravity which changes when you tilt the device. According to MEMSIC "the amount of acceleration due to gravity in 1 arc-degree of inclination from a horizontal plane is 0.017g. In order measure to within ±0.3 arc-degree the accelerometer must be accurate to within ±0.005g".
Not a lot.
The results you get are very dependant on the software in the device. Lots of calculations going on to make it behave due to the inherent non linearities and cross coupling over orthogonal axes. No reason why an inexpensive device can't be good but phone devices can be notoriously badly behaved due to poor software. Pure laziness really as the maths is well understood and any decent MEMS sensor will be well characterised but if the phone OS folk can't be bothered to get it right, with much more resources than an inclinometer maker, whats the chances of getting a bad implementation in your Amazon/E-Bay/Ali-Baba bargain.
Its not difficult to check the performance with very simple equipment. Just monumentally tedious. Wave goodby to a weekend basically. For fairly obvious reasons worst errors will probably be at small angles but you have to check the whole darn thing as there is a lot of maths going on. Hidden gotcha is how well the sensor is aligned to the axes of the body.
|Thread: Kennedy Hacksaw bearing replacement|
Concerning your worn slides can you not simply machine the top of the blade carrier and bottom to the upper sliding part so they can be bought closer together to take up the wear.
As the stroke is always the same the wear on the main slides will be even. However the unworn portion beyond the active area may foul the blade carrier and upper slide when they are moved closer together. As that unused part of the main slides is in the wind and purely structural in function there should be no problem in machining that part for clearance.
As I recall matters the Kennedy we had in our local departmental workshop had its slides adjusted to compensate for wear.
|Thread: Slitting Saw - which one?|
If you possibly can arrange for decent lubrication and some sort of positive chip evacuation. Slitting saws are one reason I put the SprayMist system on my Bridgeport. Minimum oil is enough to keep the saw lubed without fogging up the air too much and the air blast shifts the chips just fine. Feed rate needs to be enough to ensure the saw keeps cutting but not so much that chips crowd the gullet between teeth. At least the drilling provides somewhere for the chips to go in mid cut.
Job like that you can put money on locked up stresses in the hollow bolt wanting to come out and grab the saw. Lubrication gives it a chance to survive long enough for you to hear things have gone pear shape. I find that with a slitting saw sound is the best indicator that all is going well. And my hearing is poor.
|Thread: Looking for a locking stay for machine canopy.|
The friction slide thingies used on modern windows instead of hinges ought to be well up to the support job. I have a stash of used ones in the "gotta be useful" box. If you fancy trying the idea PM me and a pair are yours for postage costs.
The locking struts in Brians link are effective but, if the ones I saw are the same model, quite hefty.
Eurofit offer a variety of lid stays :- **LINK** including light duty gas struts, smallest is 50 newtons force, about 11 lb.
The ordinary folding desk stay like this :- **LINK** can quite easily be modified to work as an over centre toggle type support as described by Nigel. I did one many years ago which worked OK. Darned if I can remember exactly what I did tho'.
An ordinary drawer slide will do the deed just fine if you ass a sprung clip. In principle its easy to come up with a two position clip which releases if you push the lid beyond its holding position and re-arms ready to support the lid next time as you swing it shut. In practical its probably more works than the job is worth.
|Thread: Chosing a drill grinding attachment or machine|
The Parkside drill sharpener you got from LiDL is a "not quite right" copy of the original Plasplugs device. I have one of the Plasplugs one which works very well indeed. Blooming miracle for (mostly) flexi plastics construction.
As you found out the LiDL one generally doesn't behave unless you invest silly amounts of care in set-up and even then its a bit hit or miss. Basic inspection of the one I bought for a friend doesn't show any obvious reason why it doesn't behave although I'm less than sanguine about those "plated on to a sheet steel former" grinding wheels. If anything the plastic and moulding quality are a touch better than Plasplugs. So glad that I checked the LiDL one before a 40 mile round trip to drop it off. Even though I now have yet another shelf filler.
Totally agree that a drill sharpener should just work without faffing around and / or "interpreting" the instructions. The only acceptable process should be :-
1) Insert in carrier. 2) align by simple line or better fixed abutment for right every time. 3) Zzzipp, sharpen one edge. 4) Flip, Zip sharpen the other one. 5) Inspect and if not quite sharp adjust cut by simple screw then repeat steps 3 and 4.
That should be it every time for a simple conical or 4 facet point. Point thinning should be just as easy.
If its not just like that, right every time there is hardly any point to a jig. Although I will admit to sticking up blunt drills for a session with the Picador device. Mostly 'cos it always seemed to take a couple or three to get my eye in.
|Thread: Posilock Chuck|
A minor gotcha with the ER system is that the cutter shank needs to be fully inserted over the gripping part of the collet if its to hold correctly. For smaller sizes the gripping part is always shorter than the overall collet length. If you look inside from the back its fairly easy to see where the grip part ends.
Although the larger versions of the ER series collets can go down very small for equivalent grip sizes the smaller series collets have a shorter gripping section than the larger ones. For example an ER 11 collet is about 3/4 " - 20 mm long and the largest size it can hold is 3/8" - 9.5 mm which must be inserted right to the end of the collet. An ER32 collet is about 1 1/2" - 40 mm long and also requires a 3/8" cutter to be inserted full depth. Clearly using the larger style of collet means the maximum cutting depth is around 3/4" - 20 mm less. Its (very) roughly true to say that the insertion depth for a small cutter in an ER 11 is only half that required by an ER 32
Also the ER 11 collet nut is a lot smaller diameter than the ER 32, 3/4" - 19 mm as against 2" - 50 mm for the ER 32.
As our machines and work are generally quite small its important to consider clearances and cutter stick out. Short cutter in a larger chuck can be terribly limiting. Besides a 1/16 cutter in an ER32 looks plain silly.
Side lock screw type (Weldon) holders tend to be the smallest and can often be modified to improve clearances and give greater cutter stick out. My smaller ones get operated on if need be.
|Thread: Chosing a drill grinding attachment or machine|
The Tormek system looks well thought out too but its limited to four facet style grinds and is said to be slow. Appears to be best used with a woodworkers style wet wheel dipping into water. I'll bet it puts an awesome finish on the drill tho'. Around £200 I think which at first sight seems bit costly but if just works not too bad a deal assuming you have a suitable grinder.
I too had a Martex pistol drill driven device once. Fairly early one so they may have got better over the years. This was cheap, flimsy flexi plastic without proper shaft bearings. Worked, sort of, when it felt like it. I wasted some time trying to engineer repeatability in before launching into orbit (metaphorically speaking).
Sealey device looks good in principle but, when I had crawl over one, it seemed yet another "made too cheap" device. Drill holder and alignment devices seem on the flimsy side and you are totally reliant on the wheel holding its shape.
I've had far too many drill grinding device through my hands. Either personal purchases or "help a friend get it working" services. My experience has been that the inexpensive ones can be got to work for a while but you do have to be careful. For hobby guy who may sharpen 50 - 100 or so drills in a decade £50 (ish) and a bit of extra care may well be a good deal.
Trouble is the good, just works every time, breed are expensive. Tomek seems to set the starter price. If the market hadn't decreed that Ordinary Joe won't pay more than £50 (ish) even if "some frustration involved" there might be more market room for better devices given the usual mass production price drop. I can't see why the business end of the Kaindl i.e. drill carrier, post and slide couldn't be sold for under £100 as a bring your own grinder device.
Edited By Clive Foster on 10/08/2019 12:18:44
If its still available and the price isn't too silly the Kaindl BSG 20/ 2 :- https://www.kaindl.de/en/bsg-20-435.html#amfile_files seems to have a lot going for it.
I took a very good look at getting one some years back but a Clarkson attachment turned up at a price that would have been criminal to refuse. Dunno if there is a UK agent.
Basically a properly sorted version of the common swing over the wheel "too cheap to work well" devices but working vertically across the front of the wheel rather than sideways over the side. Thing I really like is that the drills carrier is reversible so once one edge is aligned the other one is too, an easy process if the instructions are to be believed. So once one edge has been sharpened the whole thing can be just flipped over to do the other edge. Drill carrier is ingenious being a proper pair of Vee blocks segmented toast rack style so anything between 2 and 20 mm can be held.
Instructions say it can also do point thinning, forstener bits and those brad point wood drills although the last two need a wheel dressed to shape which may not be practical. Ends of milling cutters can also be ground but the relief angles will e slightly curved not dead flat. How much that matters I know not.
I'm no fan of Drill Doctor and similar devices where everything happens inside so if it doesn't work properly, Drill Doctors have a reputation for being inconsistent, you can't figure out WTHIGO.
Edited By Clive Foster on 10/08/2019 09:56:31
|Thread: What are these off|
I'm a little surprised to hear that 48 is an unusual tooth count for differential dividing gear sets as all the listings I have include it as do to the two sets of unknown origin I (should) have about the place. (I've not seen one set for 15 years but pretty sure I haven't sold it.).
Anyway I took another look at the numbers on the shelves of that very nice case and the contents are correct for Elliot / Victoria as there are two 24 tooth gears. So far as I'm aware Elliot and the associated companies were the only folk to use that particular duplicate.
|Thread: Posilock Chuck|
You can get screwed end carriers that fit the Clarkson / Posilock chuck for the small FC3 cutters in either 1/4 or 6 mm shank diameters Ø. Works fine with plain shank ones if you add a flat to take the side-lock screw.
Better to get either a proper collet system or Weldon style side-lock holders. Shorter than an external collet system, ER et al, which can be an advantage with smaller machines which tend to run out of vertical daylight quite quickly. Spindle native collets are the shortest system but with small work and small cutters the spindle itself can get in the way.
Nothing is perfect but on balance I'd probably start by getting Weldon / side lock holders in the sizes you need and grind flats on my cutters for the screws. Probably only two or three sizes so the versatility of proper collets isn't a great benefit.
When using the Posilock do remember that the outer collar should be lightly tightened down, hand tight is fine, and the cutter screwed out as firmly as you can by hand to bring the collet into contact with outer collar. I always give the collar a quick bump with the spanner before starting work. As Mike says the system self adjusts as the screw forces the cutter out until the collet grips preventing further rotation. Starting with the collar loose can shatter the back end of the cutter.
Edited By Clive Foster on 09/08/2019 11:40:02
Edited By Clive Foster on 09/08/2019 11:40:37
|Thread: What are these off|
Looking at the labels on the dividers the gears mostly appear to be in steps of 4 or 8 teeth. If so they are a set of differential dividing gears for a dividing head as 4 (or multiples of 4) tooth steps are usual for the normal dividing head with 40 to 1 worm reduction.
The splines look similar to those used by Elliot / Victoria, Cincinatti, Edgewick, Hoffmann et al.
The Elliot set is 24, 24, 28, 32, 40, 48, 56, 64, 72, 86, 100
If the gears are for a spiral milling set up there will be a variety of other gears to generate the various leads.
For example Cincinatti supply 17, 18, 19, 20, 21, 22, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 55, 60. But the Cincinatti heads have rather more holes in the dividing plates than normal, especially if you have the wide range set, so differential indexing is rarely needed. That set is more for generating leads.
Edited By Clive Foster on 09/08/2019 10:44:30
|Thread: Lathe - dead centre wont reach the workpiece|
Morse taper extension sleeves can be got for around £15. For practical purposes one would move the centre along by the nominal length of the morse taper. Almost worth considering as a normal fit if you aren't seriously restricted by bed length as it would let you work with the tailstock barrel well retracted for much more of the time. When well extended tailstock barrels on smaller machines are less rigid than one might ideally desire.
+1 for the suggestions to alter the coss-slide angle. Mine lives at 25° as its suits the zero 2 zero thread cutting method. Other folk swear by 30° as the infeed is half the slide travel making tiny cuts easier. Needs a razor sharp tool tho'.
With a DRO system there is little need to have the cross slide parallel to the bed for controlled longitudinal cuts as the DRO tells you where the saddle is. Although the saddle hand wheel is less precise to handle than the cross slide feed screw a bed stop makes it easy to hit the same point each time. A bed stop doesn't need to be fancy. A simple block nipped up so it slides stiffly on the bed can be pushed into position by the saddle (with the tool well clear of the work) and locked up when in the correct place. A micrometer plunger makes life easier but half the time I don't bother with the micrometer on my single stop. Just use it as a dumb block.
A short screw driven fine adjuster plunger does make a stop block usefully easier to use as you can quickly get it close, move the saddle to just so and screw the plunger up against the saddle. A calibrated scale isn't important with a DRO around so any decently hefty fine thread will do. I often use 1/8" BSP for such "shift it a bit" setting screws.
|Thread: DIY magnetic DRO|
Splendid job so far.
Bin the nylon and splash out on some acetal / delrin for the cases. As Ian says Delrin machines like a dream with sharp cutters decent feed and not too much speed.
Nylon is (marginally) better to machine than HDPE but its still a miserable experience. Main saving grace is that it will behave given the right combination of fairly low speed, high feed and high depth of cut. Rather grade and condition sensitive in my experience. Sort of thing you can dial in on a lathe but not really Home Shop mill compatible. Especially if you hardly ever use the stuff and will have forgotten what works by next time.
|Thread: Polishing grinder|
Looks like LiDL have their version in the shops on Thursday 8 th.
Web page says 120 watt motor driving 75 mm (3" diameter by 20 mm (3/4" wide grinding and polishing wheels at 9,900 rpm off load. 1 m (3 ft) flexible drive shaft and 103 accessories for the flexi shaft such as sanding disks & drums, grinding points, baby wire brushes et al in a box. Box looks like wood.
All for £25. Daft!
Edited By Clive Foster on 05/08/2019 19:11:54
|Thread: Tolerance for needle bearings?|
Michael makes an excellent point about skateboard rollers. Readily available, proper bearings, more than up to the load and all the pesky details sorted so they just work.
Size isn't an issue if you narrow the seat bit slightly so the back portion sits inside the frame. Plenty of room for wheels then.
Your drive system appears to show the motor at the bottom with the screw working in compression. Wrong way round as it will try to buckle giving a bending / whipping effect that will send nut friction through the roof. The screw must be hung from a bearing at the top so its in tension. Bearing needs to be fairly free and the nut in a pivot so it all takes up its natural position. Look at the old style car "plug in the sills" side-jack. Engineering standards are applied crudity really but they lift half a ton with no great trouble.
The original EasyRizer used a simple Allthread screw of similar dimensions to what you are using and was frequently demonstrated with a Honda Gold Wing perched on it running up and down under drive from a fairly ordinary, albeit good make, battery screwdriver. If yours has so much friction that it won't lift a person you have some serious fundamental design issues.
I'd scrap the "door frame" and go for a single column with two triangulated braces back to the rear foot extensions. Picture shows the guide roller end of a hydraulic lifter rated for something over half a ton on a platform similar to, but rather larger than a person seat. Perhaps approaching double the effective overhang. Weight limits set by the hydraulic pressure and base details not column & guides.
Main tube is 2" by 3", axle pins are about 3/4" diameter on approximately 5 1/4" by 4" centre. Rollers are about 1 1/4" diameter with a 2" (ish) flange on one end. The other flange is free running. No significant side to side wobble when loaded although flanges just barely don't touch the main tube. I imagine there is reason for one flange on the roller and one loose. All steel. Made to rusty industrial "keeps on going" standards. The actual lift is between the lift guide tube and the platform. A top hung screw would work just fine. That one has a simple vertical hydraulic cylinder in a tube which connects the top of the hydraulic rod to the guides and platform. Tube also protects the rod when extended. For a screw version simple overlapping covers would seem more than adequate to keep things out of the works
Always remember being told many years ago when struggling to make one of my genius ( aka stoopid) ideas work "When your are in hole stop digging and copy something." Advice I was young and hung ho enough to ignore at the cost of a weeks worth of spare time to end up with less than stellar, albeit more or less functional, results.
Edited By Clive Foster on 03/08/2019 15:43:46
Edited By Clive Foster on 03/08/2019 15:45:23
As always with this sort of thing the devil is in the detail.
Delrin rollers should be OK. They work fine on the EazyRizer motorcycle lift which works on much the same principle albeit with single column upright and obviously stronger construction to cope with five times the weight. If I recall correctly from when I had one for about 3 weeks the rollers were rather larger than yours appear to be. If someone local has got an EasyRizer it might be worth looking at it for clues as to why yours doesn't work.
I recall coming across a reference somewhere to the relationship between roller size, loading and freeness of running which suggested that things go very nonlinear below about 1 1/2" diameter leading to much more friction than you'd expect if the design is little out.
I think the thing is twisting which will seriously increase the loads. Having hit that problem in a rather different area myself I think you need either 8 extra rollers to stabilise it in twist or to start over. That rectangular "doorframe" style upright is very flexible. A single, larger, column would be much better behaved.
I'd prefer a proper lead screw and nut to Allthread too.
Hafta say that the device reminds me of far too many episodes in the past where I "just built something simple to do an apparently simple job" rather than sitting down and designing it properly first. Result was always endless trouble getting it working properly. Easy to overlook simple but critical issues when your main attention is on the welding torch and chop saw! At 65 I'm finally getting a bit better but ....
|Thread: Searching for an Off-The-Shelf, Light-Duty, Rack & Pinion|
A chain rack isn't a bodge. Correctly engineered and properly supported it's an excellent method of accurately transmitting motion. Frequently advocated where part circle movements are made as running a short length of chain around a part circle is probably easier than cutting gear teeth.
Adcock Shipley used this type of construction to drive adns et the head tilt on versions of thier smaller vertical milles fitted out to make tooling for grinding lenses. A job that needs tob e accurate and easily done if you don't want to spend ages getting it dialed in. The one we had was certainly accurate and quite easy to use.
Chain type rack is very low friction so, in vertical application, its necessary to control any tendency to run back.
|Thread: Tolerance for needle bearings?|
Impact load, not rolling load carrying, is the big issue with relatively soft shafts.
Its essentially line contact between roller and shaft so local forces can be very high indeed if things get clonked. No great issue when you have a shaft hardened to support many years of continuous use but a soft one, although well up to a couple of thousand or so hours of undemanding use, is vulnerable.
Hopefully not germane to this application but the needle roller bearings in the original BMW K-series "flying brick" motorcycle clutch lever had a different take on problems with using unhardened shafts in needle rollers. Sealed for life bearings in an alloy actuating lever at the back of the gearbox just in front of the rear wheel with little protection from mudguard and swinging arm. As usual the sealed for life bit didn't last well. Once the seals failed water got in and rusted the bearing cage. Expanding rust pushed the needles into the fairly soft shaft giving a set of splines so nice you'd have thought they were intended to be there. Bit like the groove in a used Velocette clutch thrust race.
Getting the now expanded shaft out without mulluering the alloy ears on the gearbox that were supposed to support it tended to be an adventure. Not helped by BMW's contender for the worlds most inaccessible (and functionally dubious) E clip competition. Back in the day I fitted grease nipples to the arms for a fair few folks. Normal practice seems to be to just wear out the gearbox ears once its all seized up. Made myself very popular during a visit to the BMW factory by rolling a pocket full of mullered shafts and bearings onto the table after a "BMW are Wonderful" presentation and asking if they had sorted that problem yet!
|Thread: RENAULT DAUPHINE|
When it comes to insufficient weight on the front I guess the Bond 875 was about as bad as bad could be. Hillman Imp power train at the back. One wheel in the hole at the front with the skimpiest of mudguards in as delivered trim. Theoretically there should have been a boot floor and spare wheel up front too but Bond (actually Reliant by then) had issues making the three wheeler weight limit. Allegedly the rear and passenger seats were optional extras along with the heater. Even then I'm told all the production versions were overweight if honestly weighed.
Once knew a guy with one that had been tuned up. Allegedly a 1300 cc semi race motor in the tail (Paul Emory?). That thing could wheelie!
I treated the offer of a ride about the same way as my father did when Eric Oliver offered him free holiday in the Isle of Man in exchange for a few hours work holding the sidecar down during the TT. "I maybe mad, but not that mad."
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