Member postings for Clive Foster

Bell crank devices are primarily for changing the direction of measurement. They are inherently prone to cosine error so for accurate results the base setting needs to be with the arm perpendicular to the indicator plunger and movement restricted to ± 2.5° to 3° before cosine error sets in.

Making the measurement side arm longer increases the physical range but reduces sensitivity commensurately.

Had a slightly similar situation where I needed to get down inside a bore to verify the various errors to ensure that I had enough room to re-machine a podged up taper. I setup the seesaw probe out of a Starrett Last Word indicator kit and an indicator on my lathe cross slide using a magnetic post mount.

Something off a KTM enduro bike I think. I was very lucky that the Pratt Bernard precision 3 jaw held it accurately enough to dispense with for jaw games.

The Starrett kit uses a back plunger indicator **LINK**

https://www.starrett.com/metrology/product-detail/196A5Z

so the mounting stalk gets in the way on a set up like this.

Using the cross slide feed effectively extend the range considerably. A DRO set up would be most accurate but my cross slide screw and nut are good enough to use as is for better than ± 0.5 thou overall.

I see no reason why the measurement arm could not be made rather longer to increase the operating range but the set up is likely to get very twitchy if you go too far. 10 to 1 at 1 thou per division accuracy is theoretically possible using a tenths thou indicator but the chances of it being stable enough to actually use are slim. 2 to 1 is probably OK.

The Starrett see saw has small spherical contacts at each end and the plunger indicator has a dome end contact. This increases the angular movement range before cosine error sets in. Calculating the effects is possible but not as easy as it might seem. Size matters! In practice anything significantly more than ± 10° or so has the see saw end running off centre round the plunger end so things start to mis-behave and it all gets a bit fraught.

Bottom line is it all worked but I din't want to do it in the first place and, frankly my dears, I'd rather not do it again!

Clive

Edited By Clive Foster on 22/10/2022 11:07:24

Hopper

That's what I do except I use a lever type indicator.

Always a little wary of the bend risk when spinning something against the long, slender, probe of a dial type. One reason why the Starrett "Last Word" is the inherently stiifer and stronger back plunger type.

If using a standard plunger type with domed end probe there is a potential issue with the probe contacting the work either above or below the centre line. Inspector Meticulous can work out how much!

Some folk like to put a block on the lathe bed to support the nearest chuck jaw exactly horizontal. Its calimed to make it easier to keep things in place when twiddling the adjusters giving a more stable indicator reason.

Until the internet arrived I wasn't aware there were so many idiot stupid "claimed best(!!)" ways of lining up work in a four jaw.

Using cross slide dial and block probe was the way I was first shown. Partly because its a good training method that doesn't risk neophyte clumsiness damaging a indicator and partly because I din't have an indicator at home anyway. Just a Unique. Uber cheap, far more effective than it ought to have been, but only about 5 thou useful range so I needed to be close before it could be used. Mr Portass didn't put dials on the S type which made things even more interesting.

Clive

Its pretty normal for a chuck sitting on the short tapered spigot to need a bit of a donk to come loose. 6 of my 8 camlock mount ones need a, moderately gentle, thump with the heel of my hand to remind them to come off. The 2 that don't are big, heavy and old. Copper mallet is going too far tho'. Time for forensic inspection and careful clean up. There may be a mark or two raised just enough to grip.

If yours is the bayonet ring version of the DIN 5507 its not neccessay to remove the nuts. Should be small enough to pass through the keyholes. If its not a bayonet ring time to figure out how to make a two piece ring that can be joined in situ, I'd arrange a glued and pinned pair of stepped joints, so its much easier to use.

Realistically the plain studs and nuts version of the DIN 5507 is functionally "just" a metric dimensioned offshoot of the A series mounts. As such its not intended for regular changing.

Clive

Edited By Clive Foster on 21/10/2022 09:12:30

Quick way for the inexperienced to get close is to mount a "probe block" in the toolpost and use the cross slide dial to calibrate the adjustment. Not something to keep doing forever but its a solid training method to get the technique nailed, the "feel" established and the WTHIGO thing sorted.

Actually easier if you start off visibly out.

Process:-

1) Pick one pair of jaws and spin the work so that pair of jaws is horizontal with the work error towards you.

2) Run the cross slide forwards until the probe bar touches the work making sure the contact area includes the centre line.

3) Zero the dial.

4) Spin work 180° so the error is away from you.

5) Run the cross slide forward till the probe bar contacts and note reading.

6) Pull back cross slide then move forwards until it reads half the error.

7) Adjust chuck until work contacts the probe bar.

8) Repeat with other pair of jaws.

9) Set up indicator and finally dial in using the same process. The indicator provides calibration so its much easier.

Remember that the upright chuck jaws only need to be tight enough to stabilise the job. It has to slide without marking.

Verdict lever type indicator sets have a nice bar and upright post device for toolpost mounting. Ideal for this process. Use the bar as the probe then mount the indicator to finish off.

Using the bar as a probe and cross slide as a claibration device makes things nice and solid so its easy to get used to the process.

After about 5 goes or so most folk have the knack sorted and outgrow that process.

I reckon to get close enough to put the Verdict up by simply looking at the jaw positions in relation to the scribed circles. Three turns round and I'm done to tenths thou.

If its a ruff job eyeing up against a tool will get me into the 3 or 4 thou TIR region.

Clive

I'd be seriously tempted to weld modern 1/4" hex fittings onto the shafts of those blue pozidrive screwdrivers.

Still, in my opinion, the best and most comfortable handles for general work. Anything except gorilla jobs, either way.

Genius idea to have different coloured handles to identify the different types of end. Blue for pozi, red for phillips, green for flat. One of my biggest regrets is being too penny wise, pound foolish, and not buying full sets of all styles back in the day. But I had plenty of screwdrivers and other things screaming louder for money.

My failed no 2 posi has a shot taper for alignment duties. Lucked into a new replacement several years after they officially went off the market.

Clive

Craig

If a new headstock plate can't be got a a sensible price an effective way of quickly making a long lasting replacement is to find a decent picture, copy it and use one of the inexpensive plastic laminators to encapsulate it.

Or spend some time in a drawing or CAD program to make a nice pure black on white drawing. Rolling your own lets you put other useful bits on too or change out the pictograms for something easier to follow.

I've made several over the years using my bottom of the range Maplin A3 and LiDL special laminators. Oldest is probably 15 years old by now and still fine.

Clive

Nice job but the dodecagon section is short so its inherently unstable lengthwise and will try to tilt forwards once the collet nut and workpiece are fitted. You need to figure out some way of restraining it to prevent such things happening.

Tailstock centre on a carrier of the right height perhaps.

Even the standard style of 5C collet blocks tend to be tippy despite being much longer and having the nut at the back so weight distribution is rather better. I regard a quick thump with a deadblow hammer to make sure they are seated flat in the vice an essential part of using those. I found out the hard way that simply pushing a 5C block hard into the vice wasn't quite good enough despite looking decently level. A hex with two sides tapered at degree or three looks seriously "wrong".

Clive

Interesting but the one bit I don't see is any mention of predictive battery state of charge monitoring when using off peak power to charge the home storage batteries overnight.

Important in the UK where we have a large difference between shortest day and longest day length.

Even without battery storage I buy relatively little electricity in the summer. Long days, no heating and relatively short lights on time in the evening coupled to a bit of care when cooking and laundry mean my 4KW nominal, about 3.5 KW actual, of panels can provide most of what I need during the day. Opposite during the winter where the panels can't help much. Midsummer quarter bill £50 ish, mid winter £250 ish at real, unsubsidised current prices.

Clearly for me the major gain would be in using the battery to shift most of the winter power purchase to off peak rates. Assuming off peak is half peak I'd be looking at something over £100 a quarter saving in winter but only £50 a quarter in summer when the panels and battery can carry the load. Call it £300 + per year. Payback period is still long.

So any system I put in will always need some overnight top up to make the best shift of grid supply to off peak. But in the summer the batteries won't need much topping up. In the winter they will probably need to be fully charged.

I imagine hard limits such as full overnight charge in winter, 2/3 rds overnight charge in spring and autumn, no overnight charge in winter would go some way to evening things out to make best use of the battery. It seems that something more fine grained would be usefully better but whether that can actually be achieved in practice is a different matter. The weather apps seem remarkably effective at local hourly predictions so possibly they could drive a decent prediction as to how much power the panels are likely to make the next day. After a while an adaptive controller should have a decent idea as to how much you "usually" use too.

Clive

Edited By Clive Foster on 18/10/2022 11:47:25

Bob

Great to hear that you are still able to repair your sensors. I've got a dead one that could do with fixing in case I ever use it. One of the special ones with direct digital output you made for me for an MoD project back when I was working for RARDE.

Yours worked better than mega expensive ones from a professional supplier, which annoyed my boss who wasted money on them. Having a readout on the machine instead of having to wander back to the computer screen made life so much easier.

Given to me along with a whole bunch of non ISO 9000 compliant kit when I got the redundancy/consultancy deal "provided you agree to look after all the non-ISO kit" contract.

Clive

YouraT

Interesting link to BWElectronics. I thought the proprietor retired some years ago and that the design had become obsolete due to some parts no longer being available. Either outright or at a sensible price.

My experience is that they work well but, like all pull wire sensors, are sensitive to wire vibration. To my mind the killer app was neatly adding a digital readout to a Bridgeport or similar machine quill. It fits nicely just under the bulge in the head casting above the depth setting micrometer device. The wire doesn't get in the way of anything unlike the capacitive scales (Quillstar et al) which cover the depth setting device and the common optical scales which have to be clumsily mounted off to one side.

As Jason says the ability to fit magnetic tape inside with low profile read heads have pretty much made other solutions for cross slide readout on smaller machines obsolete.

Roll your own is a nice project but don't kid yourself that it will be up to commercial standards.

Possibly the best implementation of the leadscrew readout was that offered by ArcEurotrade to fit a couple of models of Seig lathe for a short while some years back. It sat between the handle and the slide with a digital display. Neat and effective but it just didn't catch on. No real advantages over a dial to justify the cost.

Clive

Generally the exhaust manifold / pipe breed need high temperatures to properly harden. Often you can get away with letting it dry and hoping the substrate temperature gets hot enough to more or less harden it so it sticks OK. But its a bit hit'n miss. Generally it seems that the folk who followed the instructions exactly got much better adhesion and weather protection from the folks who just sprayed and prayed.

Caliper et al paints seem to be fine if you just spray on at room temperature. Have heard that warming up a bit helps and that they are sensitive to humidity. I guess the ehatwave conditions would have been ideal.

Clive

Normally with these almost 1/4 BSF, almost M6 issues on British made things the culprit turns out to be OBA.

Same nominal diameter as M6, same thread pitch for all practical purposes but different thread form. Touch smaller than 1/4 BSF, screws in just fine but pullout force is about 1/4 of what it should be!

Clive

As Jason says. The difference is basically the smallest change that you can see / feel. With good, well practiced feel changes of the order of 1 thou (or even less) can be detected using reasonably small calipers. The big ones 12" or so are so heavy that the weight destroys feel.

It is said that highly skilled craftsmen can reliably maintain bore to rod clearances of the order of a thou using an inside / outside pair of calipers. The scatter in actual dimensions will generally be rather larger so you don't get true, close tolerance interchangeability.

I don't have any great trouble feeling a thou or so difference with ordinary calipers. But forget doing anything with it without bringing a micrometer into play.

Clive

Mike

Big, big +1 for what Jason says about the advantages of a CNC machine when you need to make large holes and do similar jobs that need (relatively) large tooling on a manual mill.

If you don't already have significant manual machine skills I'd advise skipping the idea of starting manual then converting to CNC. Just go direct to CNC.

The manual and CNC mindsets are very different. Much more so if you are proficient in 3D design.

Vastly oversimplifying. In manual machining you think in terms of tool size and build up from 2D plans. In CNC you think in terms of tool paths and 3D. Different world especially when working 12 inches to the foot scale on a smaller machine with restricted workspace.

CNC can squeeze jobs onto a smaller machine that would be essentially impossibly large to do manually. There is a reason why manual home workshop folk like me who work in primarily full size end up with a Bridgeport once we have a workshop big enough to fit it in!

Best to go for a "just works" machine.

Save up for a bit longer if need be.

Even today, when off the shelf "stuff" is far easier to get than in days of yore, converting a machine to CNC and getting it sorted is almost a hobby in itself. Sort of "this year I will build the machine, next year I'll learn to drive it and de-bug it" thing. Two years down the line you can start learning to use it for what you want to do.

Its annoying to discover mid-job that the machine isn't able to do what you think it ought to. With the best will in the world a neophyte is unlikely to be able to fully de-bug a home converted machine. At the affordable end even factory build or professionally marketed conversions have lots of gremlins and gotchas hiding at the outer ends of their working envelopes. Hopefully documented so you don't get bitten by expecting too much of the machine in the wrong places.

Not just us. Even the professionals with a million quids worth of Hemle on the floor complain. As for Haas, which are quite good really, you'd best turn your hearing aid off if you wander into moan space.

Clive

Edited By Clive Foster on 13/10/2022 10:05:54

Mike

Sounds as if you have some Fusion360 experience. If so I'd advise doing some 3D models of the components you intend to make and putting them onto 3D models of the milling machines. Not forgetting workholding and tool stickout. The latter can seriously bite if you plan on using larger drills on a smaller machine. Even 12 mm / 1/2" diameter can be too long. Buying a machine that turns out too small is a pain (how do I know).

The real world capacity of a milling machine is generally rather less than it might seem to a neophyte. Especially in relation to a lathe. Fundamentally because everything work, workholder, tooling, toolholder et al has to go inside what you see as the workspace so the space you have easily available is rather less than it seems. Its easily overlooked that a decent chunk of area at each end of the table cannot easily be reached by the tool.

Clive

Jelly

Pure, fixed frequency, electronic single phase to three phase converters basically don't, and never will, exist as a commodity item for motor drive duties.

Due to the need to supply high short term currents during start up the innards of a pure, fixed frequency converter needs to be rated to handle at least double the motor power. If you want a universal "plug and play when installed by an electrician one" three times is better. Someone is bound to shove it onto a reciprocating compressor without a leak down manifold so it has to restart under serious loads!

The inherent soft start of a VFD box running up to frequency from zero allows it to be matched to motor power with a relatively limited short term high current capacity. So all the expensive components that handle the high power end can be smaller and cheaper. These days the control gubbins, display et al are well sorted and cheap so a fixed frequency converter would, allowing for the smaller market, be at least 3 times the price of a VFD which does essentially the same thing with extra capabilities. Basically no market for Mighty Big Company.

That said I am surprised that no one has attempted to do a 220 - 415 step up version of the Eaton DE-1 series of "headless" VFD boxes. Those things are sold as a "drop in" replacement for old style contactor controls giving soft start run up and the other VFD advantages without the front end complexity. Actually a full blown VFD inside but the most complicated the installation sheet gets is three speeds. Not stupid expensive and, being intended to sit inside of the machine most of Roberts objections to Drives Direct products just go away.

Has to be said that the primary market for a bigger converter to run a small workshop is the "have multiple machines, run one or two at time" one which is largely folk like us. Tiny one. For any commercial, semi commercial or paying hobby situation the extra cost of individual VFD boxes is not relevant. Especially if you factor in proper installation with a breaker / MCB panel between box and loads. At our power levels, typically up to 3 hp, the extra cost of an inverter is mostly not a significant extra to the machine cost when got at the same time.

Clive

Counts at four and a bit turns from tight to undone with the Chronos supplied inserts for me.

I'd have put money on it being more. Just goes to show how careful you have to be when evaluating impressions rather than measurements.

Heck the amount of screw stick out when undone still looks as if it ought to be more. Even after counting. I guess its the countersink head taper.

Clive

No problems with mine either. I has to work hard for its living too as, like Jasons, it only comes out for difficult stuff.

4 threads engagement soound somewhat less than mine. Without checking 6 and some sounds more like it to me.

Clive

Jelly

I've had a 10 hp "plug & play" digital phase converter from Drives Direct running my machines for 15 years or so with no problems. It just does what it says on the tin. Slotted straight in to replace an RPC. Wiring arrangement probably isn't acceptable under current regulations but its safe with individual plugs and disconnectors for each machine. I have the (expensive) box of smoothing inductors normally advised for CNC use on the output side to kill any interference before it hits the power lines.

I have 9 machines ranging from 1/2 to 3 hp. Including a WW2 era 3 hp two speed motor on my P&W lathe with its splendidly steam punk oil immersed switchgear. I think I have had about 9 hp running at once but normally its one machine in use and maybe the Rapidor power saw (3/4 hp) chopping stock for the next job with the 3 hp motor on the hydrovane compressor kicking in occasionally. I'd be a bit dubious running a reciprocating compressor of the same nominal capacity of the hydrovane due to the heavy draw during run up.

The Drives Direct systems are expensive but I understand there are some significant internal modifications to the innards and programming to ensure the box doesn't fault out. Trying to start machines when connected to a VFD running at 50 Hz will cause a modern inverter to fault out and stop.

Drives Direct say their boxes can safely start a single machine up to half the nominal power rating. I reckon 1/3 (ish) is a more sensible de-rate.

I got my box second hand as a temporary measure whilst I found an electrician to hook up the three phase incomer I'd had installed. Nowt so permanent as a temporary job. Gave up on electricians after about 5 no shows!

I've done the replace with individual inverter maths a time or two and came out with rather better figures than you last time. If starting in 2022 individuals would be the way to go for me. Reckon I'd actually do better than break even selling the Drives Direct box and installing individual units and changing the two speed motor.

Clive

Thanks for an interesting and informative discussion.

The 64,000$ question beyond the need to maintain the CCTV is what of her devices don't automatically reset after a power cut. I suspect the need for continuous CCTV and associated internet connection is indeed, as V8Eng says, to help keep the insurance company happy.

So Plan A will be to look into one of those battery back-up, multiple 12 V output, boxes like this :- **LINK**

https://www.ebay.co.uk/itm/323995263949 Electrical CCTV Camera Power Supply Box 5/9/18 Channel Back Up Battery Option

Which should keep the surveillance kit and internet connection live. Possibly also any other 12 V kit that doesn't auto restart properly.

Dunno about her gas boiler and control. Its fairly recent install but so is mine and that needs manual intervention to bring it back up after a power cut. Mains back driving isn't really an issue if the system always runs off the battery via the inverter with a float charge system to keep it charged when the mains is on. So its fully isolated via the charger.

I'm a little surprised that the big battery system that Samsaranda has on his solar panels doesn't automatically handle the mains disconnection and reconnection thing as it seems fairly simple to implement. Basically whacking great normally open relay held on by mains power with a suitable control delay before reconnection! Something I need to look into when I get a battery system for my panels.

The big surprise for me was just how much battery you need to keep CCTV up and running for decent periods. Its clear that normal UPS systems aren't made for this job. To get the battery capacity you need something with a silly oversize inverter on the output end as common specification is only 10 minutes or so at full load.

The camping systems are interesting but I'm skeptical of reliablity on permanent float duties.

Thinking I really need to get my generator permanently linked in just in case. One of the uber quiet Honda EX5500 beasties with a twin cylinder water-cooled engine. Old but much less noisy than anything modern.

Clive