Member postings for gerry madden

Thank you very much for your searching Ed. I'll do some digging see if I can find one somewhere.

Gerry

Well, just done some suppression trials on the drill and sure enough I create some sharp pops and bangs on MW and LW as I cycle the trigger on my drill. Nothing on FM thankfully. There was no interference when running at steady continuous speeds though.

It's not often I listen to these bands when I'm drilling so wont be too personally affected but if I can buy a new suppressor I will.

What I did also discover whilst playing is that when cycling the trigger, occasionally it rotationally kicks much stronger than normal suggesting that the electrical power is being fed in suddenly rather than progressively. This only happened at small trigger movements at low speeds - exactly the conditions that have caused my suppressor to pop and my trips to flip. I don't think this is caused by mechanical deficiencies in the switch unit as this all looked good. So perhaps there's some speed/current conditions where the electronics create some spikes. May be this is what's caused the suppressor to fail a few times.

Gerry

Nick, since this is at least the second time its done this, would it imply that, as Andrew suggested, it is self-repairing to a degree and so must still have some 'suppresance' left in it even after a second loud pop ?

Ed, thanks for your offer. The model number is NHP1300S. I did some trawling on the web last night and references to this model tended to show up as diagrams and parts lists for HP1300S, which is not the same. (I think this ones's a fixed speed with a simple on/off switch and no suppressor.) And stranger still, I found the original instruction booklet at home from when I bought the tool and the diagram in respect of the switch and capacitor didn't match with reality very well at all. Its almost as though my variable speed version was a short-term upgrade that wasn't expected to be in production for long so they didn't waste too much time on documentation But if some OE parts are still available I might just buy them to keep the old girl going.

Gerry

Thanks all for the interesting points.

The drill is double insulated so no earth leakage. Not sure how then I would would get a L to N differential to flip the trips ?

There is some blackening on each end of the capacitor but decided it was probably dust from the seams of the clam-shell where the ends of the cap. resided. Perhaps I'm wrong. Your thoughts would be welcome.

Here's some pics.

Hi all you electrical specialists....

I've had a Makita variable speed drill for nearly 30 years. In the long distant past I remember on one occasion getting an electrical 'pop' from around the switch area when running at low speed. It did it again yesterday, only this time it tripped the circuit breakers in the garage (where I was working) and the one in the house that feeds the garage. Thinking it was probably 'terminal' this time, I immediately stripped the drill to see what inside had failed.

I stripped the switch unit (which contained a small circuit board) and could see nothing amiss. No damage or signs of burning. I cleaned it all up and relubricated with Barrierta and reassembled. The device next to it was a dual capacitor. This looked old, a little swollen, but not conclusively busted in my modest opinion. So I put it all back together and tested the drill. All is well !

So what inside the drill might make a big pop noise, trip the trips and yet appear to be unaffected / undamaged ?

Thanks all. Vidar you put me on the right lines and got me thinking. I found lots of data for screwjacks and it comes down to lead angle of the thread and CoF at the thread. So in my case its going to be about 20%. And when plug this figure in I end up in Andrews ball-park ! Clever stuff, maths

Gerry

Hi All,

I'm just calculating the clamping force I can get using my large but ancient vice. Its mechanical advantage comes out at around 260 which would give some theoretically big forces but there must be some losses. Does anyone here have an experienced-based suggestions as to what this might be ? 10%, 50% 80% ?

Well that was a welcome Xmas break as I finally managed to finished my crankshaft pulley in stainless steel.

The issues I had with making this one was putting in the corner radii. I have a brazed carbide tool with a tip radius of about 1.5mm. I thought this would do nicely. Unfortunately once the cutting chip-width exceeded about 1~1.5 mm seriously bad structural vibrations started. I tightened everything, reduced overhangs and even tried cutting on the opposite side but failed to make any significant improvement in the cuttable chip width. I guess the machine is simply not rigid enough to plunge this size tool into the workpiece.

In the end I had to form the radius by lots of small bites that blended into each other then clean up with emery cloth. (You can still see a little bit of a chattered surface though.)

Perhaps the material I was using wasn't the best in machinability but I see indexable lathe tips for sale with radii of up to around 5mm for wheel profiling and wonder how others get on with these ? Or perhaps there's some tricks I don't know about ?

Hi All, just an update...

After careful thought I went for making a big hole. It was a kind of 'in for a penny in for a pound moment' with the advantage that I can put my hand in to attend to some other things as well, as they become necessary.

Jason B - Thanks for the Richon link. What an interesting site that was too! I ended up buying a 105mm diamond core saw and it took about 10 days to arrive. I cut a piece of ply and fixed this on the tiles with single a screw. The saw cut through the tiles went beautifully with only the tiniest of chipping at the edges of the hole. The cutting part took about 10 mins and I wasn't trying.

I have a sheet of white acetal for the cover. I'm hoping a soak in some coffee should give it a coloured tint to help it blend in with the tiles.

As always, excellent food for thought. Thanks all. …. I learn so much every time I post on here !

Gerry

Hi experts,

After some guidance again... A builder, god bless him, has done a superb job in boxing in my mains stopcock with tiled panels. He obviously thought access through a very heavy removeable granite cover and a long reach down at a funny angle would be a piece of cake. I knew 6 years ago this was going to be a pain and now that I have leaking ball-cocks and other things to attend to I find that is definitely is..

My plan is to make a hole through the tiled panel to gain direct access to the tap. I'll machine up a plastic cover for the hole when not in use.

I'm thinking I need to get a big SDS drill and a diamond toothed hole saw. The tiles, I know from experience of drilling holes for other brackets, are very hard and 10mm thick.

Is a hole saw the most sensible solution or should I do things differently ?

Well, as you all know I have been machining up some pulley sheaves.

Before setting the top-slide I hunted around on the internet to find the correct flank angle. I was advised by the belt supplier that it was a 'Z' section belt with a 10mm width at the top and a radial thickness of 6mm. (The internet suggested that this type has an included angle of 40 degs. I therefore set the top slide (with a DI) to machine 20 degs.

I have checked the finished parts by several methods) and I have no doubt that I'm within 0.25 deg of the target of 20. Unfortunately neither the new or the old belt seems to be a particularly good fit with my 40 deg angle pulley.

Now, I had assumed that the pulley flank angle would be the same as that of the belt. I had previously measured the used and worn pulleys and decided that they were pretty close to 40, so 40 they must have been when they were new ! Unfortunately, now that I check them more carefully they look to be more like 34 degs!!!

Unfortunately this would seem to tie up with more information I have gleaned from the web suggesting that the pulley angles for a Z drive can be 34 or 38 degs depending on pulley diameter.

So is this really correct or am I confused and mislead by alternative facts in the web ??? Are drive pulleys really made to a different angle to the one on the belt ? Might this be something to do with the bending of the belt causing the inner zone to compress and get fatter ?

If you experts confirm this is the case it looks like I will have to start the machining all over again

Gerry

For the second of the small pulley sheaves I got some tips designed for stainless steel cutting. They look like the one on the right, with the aluminium cutting tip on the left.

Really pleased with them. They seem to cut just as well at any speed and leave a nice finish but usefully don't have that rather fragile sharp edge which is so easily chipped.

I have also leant to get along with the swarf which I really didn't like initially. Stainless steel swarf is quite crushable, unlike aluminium. With a pair of tough gardening cloves on you can collect it and compress it into quite manageable volumes.

Altogether a great learning exercise.

Hi all and thanks again for your comments. I should say that I'm privileged (?!) to have my workshop in the house (and in a carpeted room whats more) so I cant really use cutting fluids. Occasionally I dab on a bit of white spirit but that soon turns to smoke and generates lots of complaints. HOWEVER, my problem of BUE has been solved.

I discovered that the cause is (as Andrew mentioned) the re-digestion of swarf into the cutting zone. By stopping the process and clearing the build-up, or changing the speed allowing the spirals to shoot off in a harmless direction the BUI simply never happens. And even if it does happen, I also discovered that just ignoring it and pushing on will often cause the BUE to break off and get everything back on track.

The only harm the BUE seemed to do was make a noise and mess up the surface finish. A light finishing cut takes care of that.

By the way, the U/sonic cleaner did help but for all the wrong reasons. A quick 5 minutes had no effect at all. But as an experiment I left the tip in the tank and by next morning the aluminium had corroded. The U/S had no difficulty removing this so I just repeated this giving it 5 mins per day and a week later there was no sign of the aluminium and the carbide itself was as good as new !

I have started machining the face of a large bar end of aluminium 150mm max diameter at about 1000 RPM. All went well for about 20 mins then suddenly the cut goes to the dogs.I take the tip off and see this....

It won't pick off with a finger nail and knowing how fragile the tips are I don't want to force it. I've not had this issue with any previous aluminium cutting with these inserts.

Any suggestions on (a) how to remove it safely and (b) how should I change my conditions to help avoid it again ?

For now I've put the tip in an ultrasonic cleaner but not hopeful this will do much really. I suppose I could heat the tip to the melting point of aluminium and let it drip off

Gerry

First piece finished...…

The biggest challenge firstly was the swarf. Horrible razor sharp stuff and you have to keep stopping to clear it or it gets caught in the rotation and flails around dangerously. I discovered that cutting slowly keeps it in more manageable spirals and later with a big pair of leather gloves you can crush it up nicely and reduce 3 carrier bag-fulls of the stuff into one.

Secondly the 20 degree flank angle meant the cross slide and top slide knobs tended to interfere and I had to work with the topslide almost at its positional limits. This meant that the slide was getting a bit loose in its gibs and caused the 1mm-pitched grooving you can see on the periphery. Its not really as bad as it looks in the picture so I'll run with this imperfection. But anyway I think I can avoid this on the next one with a bit more jiggery pokery.

The bolted mandrel was a fantastic success Hopper and worked perfectly. Not even a hint of slip at any time so.

The CCMT aluminium cutting tips worked beautifully at the lower speeds of 300~500RPM. At 2000~2500RPM they frequently chipped. I couldn't work out at first why the cutting quality became progressively worse until I looked at the cutting edges with a microscope and found the reason. This issue wasn't really obvious by eye.

Ian P, I think the reason for the severe wear might be the speed. I didn't think about this earlier but the engine runs almost continuously at a 5000RPM so the fan will be doing about twice that. I do know from the past when I've fitted new pully sheaves the system/belt is almost wear-less. So I don't think there is any other defects in the set-up like misalignment etc.

Now I just have to decide if I tackle the 2nd small pulley or have a go at making the large one.....

Gerry

A while ago I reported on making stiffness/compliance measurements of the spindle in my mill. I measured about 3 microns/Kgf in the X axis and 0.9microns/Kgf in the Y axis on my Wabeco.

It's quite and easy thing to do. Just put a drill in the chuck, set a DI on to it, then pull the drill shank in the horizontal plane with a spring balance. Then divide the total deflection on a DI by the load that you apply.

In my case I found that I was able to improve my X-axis figures by about 30% by re-machining the mounting face of the head casting which sadly wasn't very flat.

Spindle stiffnesses are never quoted by m/c tool makers or sellers which is a pity. But if people on here were to do this kind of check it might help those looking to buy new machines, or even encourage manufactures to improve the breed.

Gerry

Thanks again all for your comments.

Ian P, yes you are absolutely correct. The belt adjustment is by shimming between the pulley sheaves on the fan shaft. The other side is thinner material though 1.6mm as opposed to the 2.6mm of the one in the picture. It gets away with this because its backed up by the plastic fan hub.

As regards the corrosion, the pics don't show the state it came out of hibernation in. They have been cleaned up with emery and wire brush, then operated for about 10 hours. Unfortunately, even in this condition, still black dust being generated indicating belt wear. But the bigger issue is due to the material removed from the pully flanks in clean-up (and the belt of course), I run out of adjustment. I can remove all the shims and still the belt is too loose. Of course I could just start machining off material from the centre portion of the flanks but then the 1.6 thick sheave isn't going to be happy about that. As you might have guessed by now Ian, the engine is from a small aircraft so my solution has to be robust rather than 'experimental'.

Hopper - I think your 'process sequencing' is the right one and have nearly finished the nutted mandrel and will let you know how it goes.. I thought it might slip because for some reason I imagined the torque was going to unscrew the nut. Its actually going to tighten it ! Also, I have to put a notch in the bore of the sheave to get the pulley over a key on the fan shaft so if necessary I can use this feature for manufacturing also.

Gerry

Ok chaps, I'm back to pick your brains again !

My smaller pulley is comprised of two sheaves. I have thought long and hard about how to hold the stock in order to create the required shape. But this stainless (303 grade) is relatively tough stuff to machine, not to mention the swarf that comes off it, so I'm quite keen to do it the right way first time.

It doesn't look feasible to machine the flanks holding the part by its OD in the chuck so Im thinking of this... Make an expanding mandrel to hold the part by its bore. Machine the inside face and OD. Remove turn around and machine the outside. What worries me is that the mandrel wont be able to cope with the cutting torque when Im working on the outer edges so I might need a clamping nut to make it secure. Then I have to think about how to hold the part it for removal the metal that will be left under the nut.

Perhaps if got it all completely wrong ?! Would be interested in your ideas on this one ?

Incidentally, Ive been using the aluminium cutting carbide tips cleaning up the offcuts. I was looking for a speed where the swarf would come off in fine chips but between 100 and 2500 all I get is nasty razor wire spirals. I think I will try some of the tips that are designed for SS and see if they perform better. The 'standard' gold coloured tips didn't seem to work well at all on this material. Lots of screaming and at the higher speeds an interesting red glow at the junction of the tip and the workpiece

Thanks all for your useful and thought-provoking comments. I decided that other than machinability, brass didn't have much going for it. Today I was able to get some stainless for my small 70mm pulley and a big lump of aluminium for the larger drive pulley. So next year I'll be able to tell you which is better, at least in my particular application anyway.

Ian P - I agree its puzzling we don't see this issue more often in cars. The pulleys (polyvee) on my recent cars, (one of which is stored over winter) never seems to have the shiny groove flanks even with regular use that I see on my 2 stroke engine. I wonder if automotive pulleys have some kind of treatment to resist corrosion. One thing I have noticed on my 2-stroke engine pulleys is that the corrosion occurs where the belt rests on the pulley. You'd expect the rusting would occur only in the exposed areas. So is the belt cording material a little bit hygroscopic I wonder ?

Ian - plywood isn't such a bad idea. 70 years ago when materials were short, some large bearing cages were made in plywood. If my application was less important, I might have been tempted to give it a try.

Gerry