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Member postings for Simon Williams 3

Here is a list of all the postings Simon Williams 3 has made in our forums. Click on a thread name to jump to the thread.

Thread: AC Capacitor
26/03/2019 19:24:30

Hello Raphael, good evening again.

As I said before I don't know this particular machine, but I'd be leery of using motor oil in any compressor because of the detergent content. Compressors suffer from condensation by virtue of the water in the compressed air coalescing on the internals; this water gets mixed into the oil and emulsifies if the oil has a detergent content. You actually want an oil which does the opposite and is hydrophobic, i.e. it rejects the water, not dissolves it. Of course - just like a car engine - if you get water mixed in the oil it not only goes a nasty grey sludgy treacle but it also ruins its lubricity properties.

I spent a lot of time in a previous life playing with Atlas Copco industrial compressors, mostly reciprocating, some screw compressors. The reciprocating compressors normally used an oil called POA which stands for poly alpha olefin, and which has the long life lubricating and water rejection characteristics. Others will hopefully tell us if this is a suitable lubricant for your application, if so it's available in the after market quite readily. It's not cheap but it certainly isn't as expensive as the prices you mentioned above.

We used to take this oil and discard it, which sounds a bit barmy but we used the compressors in the food industry, injecting compressed air directly into the food process. This meant that the compressor oil had to be food safe, so we actually used an oil made by Rocol called FoodLube. Again I don't feel confident to say definitively that this is suitable for your compressor, but I'd be happy to give it a go if it were mine.

Hope this helps, I'm a bit reluctant to recommend an oil, but I'm pretty certain straight motor oil isn't compatible with your compressor.

Best rgds Simon

Thread: Newbie with a chuck query
26/03/2019 10:09:54

Original post says he has three pinions, 3,3,1 ; can't see that's going to matter too much. It's not ideal, but it's a second order correction.

He also has three jaws which I would call a mismatched set in that he has got 1,2,3 but different serial numbers. How much error this will introduce is anyone's guess, but if they fit in the correct slots (and subject to the above comments about missing teeth or a damaged scroll) this should give a usable if not precision chuck. There's a lot of good work come out of a poorly chuck by dint of machining everything at one setting.

If the concentricity is close but not close enough then we might be into jaw grinding territory. I'd be chary of committing to this except as a last resort.

Some of the posts above seem to have got fixated on not having a 1, 2 3, set of JAWS, this isn't the case.

What would be interesting to know is how far out of true the chuck is with all three jaws fitted. If it's country mile out then there is something wrong with the teeth or the scroll. This might be helped by shuffling the jaws or putting them in with one tooth delayed, but it's a long shot and is going to be a PITA for all time, Interesting but not serviceable.

Given a lathe is only as good as the chuck, bite the bullet and buy a new (i.e. replacement) one. Nothing wrong with buying another second hand one with all the jaws but be choosy. Alternative is three (six including the outside jaws) new jaws - money well wasted since we don't know the scroll isn't damaged and we've still got the riddle of the mismatched pinions which indicates this chuck has some sort of bodge-it history going on.

HTH Simon

Thread: AC Capacitor
25/03/2019 23:36:48

+1 from me, Bill got there first.

Just to be sure though, you have checked the compressor is running freely and is not trying to start against the stored back pressure from the air in the tank? Hopefully there is some sort of decompressor or venting system so that the motor only has to accelerate the compressor internals up to speed. After the motor has got going then the compressor starts pumping and generating back pressure.

If the stored back pressure is on the compressor piston when the motor is stopped then that can make it stall, though usually it will at least try to start.

I'm not familiar with the compressor you have, but most of them have some sort of decompressor controlled by the pressure switch. There is usually a non return valve located at the pressure tank, and some sort of bleed off valve which allows the air trapped between the compressor outlet and the tank non-return valve to bleed away when the pressure switch shuts off the motor. Often the bleed off valve is part of the pressure switch mechanism.

But a capacitor is first suspect and a cheap fix. It worked for my shower pump, which exhibited exactly the symptoms you describe.

Best rgds Simon

25/03/2019 22:59:47

Hi Raphael - certainly those symptoms sound like it is the capacitor that is the problem - I assume the shut down after failing to start is the overload trip popping.

A replacement shouldn't be too expensive - here's one such , I just put "motor start capacitor" into the search string on ebay and this was the first entry. You need to scroll down the page and select the uF value to suit.

The voltage rating looks like it is way over the top, but this isn't so. In fact the 270 volts RMS rating is approximately equivalent to the 450 volts of the advert, as this is a peak to peak value.

Try this link as a starting point - you may wish to find an equivalent located closer to you to keep the carriage charges down.

Motor start capacitor - select 50uF

It doesn't generally matter too much to get the value spot on the same as the original - the actual uF value of the new one will be subject to a wide tolerance - typically +/- 20% at least.

Good luck, do let us know if it cures the problem.

Best rgds Simon

Thread: Hofmann Rotary table owners?
20/03/2019 08:20:23
Posted by Peter F on 19/03/2019 23:42:57:

Is that allen screw to the right of the logo have anything to do with it

Yes.

The worm is located in an eccentric cartridge, so loosening that screw allows you to turn the (eccentric) worm bearing. Not only does this permit adjustment of the backlash, you can also disengage the worm from the pinion allowing the turntable to revolve freely. Useful for setting up.

HTH Simon

Thread: Strange Myford Motor Fault
19/03/2019 17:00:26

Sounds like the symptoms of a shorted turn within the windings, which is difficult to diagnose with a multimeter. Suggest it's time to take it to a rewind house and see what they make of it. If is a shorted turn it might be possible to detect excess current draw, but the no power out for whatever power input is a trip to the scrap pile.

It's likely beyond economic repair whatever it is, so buying a replacement is probably the cheapest - or at least the most cost effective - option.

Thread: 1/2" x22tpi tap?
19/03/2019 15:11:15

Just on the outside chance that the tap has been labelled wrongly (typo?) have you checked that it is 22 TPI and not something more familiar?

Thread: R8 instead of MT3
19/03/2019 12:18:54

Do you have the means to turn a drill with an MT3 shank? If yes go R8 on the mill, if no go MT3.

MT3 won't fit in an R8 adaptor, there's not enough meat left so there is no such thing as a compact R8 to MT3 socket.

I bought a Rong Fu mill drill a long time ago, and agonised over this choice as I thought then that the R8 was by far the better choice up the spout of a milling machine, but it made my stock of MT3 shank drills unusable. I swallowed hard and went with MT3 and have never regretted it even if the comments about the taper being a pig to eject sometimes all ring true.

I agree with Jason's comment that ISO30 is a better choice. If only....

Thread: Heavy Machine Removals - any suggestions?
19/03/2019 12:04:54

Vic Haines Transport in Pershore will oblige, try ringing them on 01386 553288. Lorry with a loading crane or palletised or whatever. No connection, we use then a lot at work and they travel all over the country. I've had stuff on a return load from Scotland no trouble, prices as good as anyones.

In a previous existence I used Charles Russell Transport in Tewkesbury. Might be worth a try on 01242 680678. I see their lorries all over the country, so they're still at it.

No connection to either - just a happy customer.

HTH Simon

Thread: Workshop insurance
17/03/2019 10:49:25

I've gone over to NFU Mutual, on the basis that their workshop insurance actually expects you to have tools and welders and chainsaws etc in your workshop, unlike a nasty experience with one of the major high street brands.

Usual disclaimer applies, and no I'd better not name the "other brand".

HTH Simon

Thread: If starting again, what would you buy with a budget of 5k?
10/03/2019 20:32:01

Well, to answer the question the OP posed :

Got to be second-hand if my budget is only £5K, can't stretch this far enough with new machines. Take my chances on buying a dog, make sure to try before you buy, and only part with my hard won loot to a dealer who talks the talk and walks the walk. Buy privately if you can but be very choosy.

What I would buy would be a Colchester Student or Triumph 2000, plus a Bridgeport. probably Mk1. I have probably spent my budget of £5K by this stage on the machines, and will be saving my Christmas money for chucks and tooling for the foreseeable future.. But I might be lucky and get enough to make a start.

A Start on what?

Not model making, not with that machine line-up. I'm into more agricultural pursuits. Hopefully I can get a stick welder out of my budget as well.

As I read the original question in the thread title, this wasn't about the OP looking for advice, it sought a personal opinion as to my own preferences for pursuing my interests.

But I could be wrong. (Again).

Thread: Bowl shaped propellor
08/03/2019 20:43:16

Hi all, good evening.

I've been watching a number of videos recently involving rotating propellors, typically on the front of some sort of aircraft. I think I can get my head round why the blades in stopped motion are curved in the plane of rotation as the tips are travelling faster than the hub, so the strobe effect of the video camera frame rate freezes the propeller motion at different points in its rotation. Or have I got the wrong end of the stick completely?

Whether this is right or no, I'm blowed if I can understand why film of a rotating propeller taken from a position behind the plane (no pun...) of rotation distorts the shape of the blades so they appear bowl shaped. This maybe something to do with how digital cameras create the illusion of frame rate?

Does the same effect ring true for the spokes of a revolving fly wheel with a solid rim? So the spokes go bowl shaped? If so the rim should be out of line with the hub, no that doesn't seem right.

Any thoughts?

Thread: Tom Senior Type E Main Column Issue
02/03/2019 13:48:25

Hi Jeff, have you by any chance got a bruise or a dink in the surface of the column where it enters the base casting just enough to make it a tight fit?

Good luck

Simon

01/03/2019 19:29:01

Rancid grease gumming up the socket in the base casting?

Try flooding it with penetrating oil and see if it changes.

Rgds Simon

Thread: Sliders too tight
06/02/2019 13:27:09

Well, I know it was me that said don't start cutting metal YET, but I think the time has come, it's pretty clear that the slides are not as original, and the way forward is to subdue some of those mountainous looking peaks.

I'm going to raise a fire storm by saying that I think the dangers associated with embedding particles of grit/abrasive are overstated. Whether they are or no it doesn't seem you have any alternative. Go for it, particularly now you have it all in bits and can clean it afterwards. I feel you want something more aggressive than 3000 grit, though that may be a knee jerk reaction to an awful lot of magnification. If it was me I'd glue a bit of 800 grit wet or dry silicon carbide paper to a lollipop stick of the right shape and try scuffing over the rough bit, though rather gingerly to start with. Use it wet to keep it cutting cleanly, say paraffin or something like that though water will do. Once you've got the worst of the damaged surface under control polish it with say 1200 or 1500 grit. It's a sliding surface so it doesn't have to be mirror finish and a bit of surface scoring will carry the lubricant better.

I also feel that once it is re-assembled almost any lubricant will suffice - it's only got to slide so a bit of best lithium axle grease is as good as any.

I'm guessing wire wool won't tackle the peaks preferentially to the troughs in the same way a flat abrasive surface will.

Like the idea of a fine diamond coated lap if you can find something suitable.

Good luck , do keep posting the updates.

Best rgds Simon

Thread: A couple of forum Q's
05/02/2019 12:37:11

I know the discussion above is about number of pixels, but that relates to the file size of the image. I've taken to emailing myself the picture I want to post, which automatically (W10) re-sizes it for a sensible number of bytes rather than the original. Typically 2 - 3 Mb drops to say 100Kb. It only seems fair not to clutter the forum server with whole lot of unnecessary file space.

Are you saying this isn't necessary, and the album upload process re-formats/compresses the file size to reduce it to a sensible number of Kb?

The process doesn't seem to impair the definition of the posted picture, though that may be the limitations of my screen (and eyesight!).

Best rgds Simon

Thread: Cut a slot in round stock
02/02/2019 10:26:16
Posted by martyn nutland on 02/02/2019 08:36:39:
 
To make the pivot I'm using a surplus Austin Seven gearbox mainshaft which is a nice bit of 'stuff' and because the gears would have been keyed to it, is not in itself hard. Its about eight inches long and 19 mm in diameter. and I turned it down to 14mm which is the only really critical dimension (hole in fork).
 
I am holding it in a collet block with an ER32 collet in a Vertex 4 inch vice on a Warco Economy mill. I have about 35 mm protruding out of the collet and for the later/heavier cuts I supported the overhanging end in a vee-block. Prior to that the collet block tended to tilt downwards.
 
Thus, I think overall rigidity is an issue.
 

Rigidity is always an issue! But that ain't the whole story.

That bit of mainshaft may not be hard, but I bet it's tough as old boots. Cutting a deep slot like this is difficult territory, without trying it out on some difficult material. For curiosity, try the same procedure on something more forgiving and see how much better a result you can achieve.

Your slot drill, if we mean by that something with a cutting edge which meets the centre of rotation of the end face, should plunge perfectly happily. But, again, trying to do that in the material you are using may be easier said than done. If it doesn't plunge as easily as it would if you were just using a standard twist drill then there is something wrong with the cutter geometry, though a tough material won't help things. Drilling a pilot hole is a good work-round, but you shouldn't need to.

The other thing we've not mentioned is the actual cutting procedure. In principle you can cut a slot by going to and fro, but you maybe running into problems with cutter deflection so try cutting in one direction, then returning to the start before feeding down for the next cut. IIRR Jason's series of articles in MEW on milling for beginners include some comments on milling about the geometry of cutting edges and how the number of flutes can affect the accuracy of the finished item. Make sure you are not re-cutting the swarf, that will deflect the cutter erratically and frustrate your best endeavours.

But good to hear you got something functional, if not pretty. Your mill is plenty capable of doing pretty but it may need a bit of fiddling with the cutter geometry and sharpness also the technique to get there.

But the lesson my milling machine has taught me is that it always needs a rigid set up, and I have learned that time making sure the work is held securely is always well invested.

Best rgds Simon

Thread: Repairing a hole
01/02/2019 11:08:11

+1 for spark erosion, don't know much about it but I've had much the same problem - albeit a bigger diameter - solved by someone who had the kit and knew how to use it.

Drilling is asking for trouble, and offers every chance of making the problem worse. Next paragraph potentially should be a thesis on how to remove a broken carbide drill from a blind hole. (Spark erosion!)

Can you soften/anneal the workpiece. If you coat it in soap and then wrap the item in iron wire most of the oxide will be kept off it. Then you might (perhaps, with a following wind and a whole bag of luck) stand a chance with a drill bush and a reamer. Perhaps. Now re-harden. Oh yeah!

Make another jaw from scratch. Spark erosion is suddenly looking economic.

As for removing a roll pin, rumour has it if you can stuff plasticine or putty down the hole in the middle, then insert a wire piston (tiny twist drill?) and give it a whack. The hydraulic forces will push on the bottom of the pin and (maybe) expel it. Perhaps. Seems like a bit of a fairy tale, but it works with bigger things like bearing outers.

Thread: Sliders too tight
01/02/2019 10:09:07

+1 from me for NOT cutting metal - at least not yet. I can't believe those jolly clever chaps at Nikon made something which isn't fit for purpose, they are much more diligent than that. This is the sort of thing they are good at.

Aluminium as a slider in this application is perfectly fine, and if it galled up you would be in deep trouble, it would be jammed absolutely solid. I feel this is more about age, and the sticky-ness of rancid and probably dirty grease.

WD40 is good at freeing things, but after a short time - a day or so - the residue it leaves starts to dry and go sticky again, so it may be that the cure is worse than the illness. I would be using IPA or even brake cleaner, carburettor cleaner is good too as it dries faster but it can pickle the paint. With the old grease out of the way the slide should move easily - too easily, so add some oil or grease to slow things down again. If the slider is still too stiff when you have cleaned it then there are still grease remnants in there, or a burr from someone else's heavy handed-ness trying to rectify the same problem.

I would bet almost anything that the slide doesn't need to be adjustable as it is made accurately enough to control the clearances. This isn't a machine tool its a precision instrument.

If I've understood correctly, you have managed to get the assembly with the stuck screws off the microscope. If they were assembled with Loctite your best bet is some heat - low oven, say 120 C or so. Loctite is pretty much immune to solvents - so soaking them is not going to help. If they are stuck because of the passage of anno domini, try some white spirit or paraffin.

HTH, go gently at it, and don't start introducing abrasives unless you can be sure to clean the residue out again afterwards.

Simon

Thread: Cut a slot in round stock
31/01/2019 23:32:01

By dint of washing it with coolant, or simply blowing compressed air at the cutter, make sure that you are not trapping and re-cutting the chips. Otherwise this is about stiffness/rigidity of the set-up and/or sharpness of the cutter, which could well lead to a conversation about climb milling.

If you can first drill a hole right through with your slot drill and then wash the chips down the hole it gives them somewhere to go.

Quite a difficult thing to do actually, so some photo's of the set up would help to show what is going on.

HTH Simon

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