Member postings for gerry madden

Good advice as always. Thanks for your mass of useful info.

Gerry

Hi all,

I'm currently renovating an OMT toolmakers microscope that I have recently bought.

Lots of the adjustment knobs and screwheads are rusty. I'm cleaning them up by alternating them between dunks in citric acid and spells in the ultrasonic cleaner. The acid does most of the work but the u/s cleaner initially degreases and then removes the heavier layers of rust. The process is slow...well too slow for me...so I'm just wondering if I can sensibly put my acid mix in the u/s cleaner to speed things up a little ?

I've not heard of anyone doing this before and cant think of any pitfalls, but just thought I'd check with others who may have better knowledge in such matters.

Gerry

40 years ago I suffered an oil pump failure on a VW Polo. I took it apart and discovered that some lugs on the inner gear that engage with the crankshaft had worn off. Since it looked like steel I decided I could easily braze some new lugs on and save myself a pile of cash. I cleaned the ring up nicely and started to heat it but it started smoking. Since I was doing this in the g/friends flat (on the cooker to be precise) I thought I had better stop and give the ring proper clean this time. Started heating again and yet more unpleasant smoke was emitted. Strange I thought, must be some surface residues in those difficult to reach places. Gave it yet another clean and sure enough after a few minutes along came the smoke. It soon dawned on me that the ring was a sintered component. What I thought were machining marks on its surfaces were just replicas of those in the mould from which it was formed. Anyway I decided as I'd got this far I might as well carry on to the bitter end and see what happens. So started to heat the ring again things got quite noxious but I persevered and eventually the smoking stopped. I completed the braze and cooled it under the tap. Of course by this time the ring was an ugly mess from all the carbonised oil and I really wasn't hopeful of even a half decent result. But I cleaned it all up and discovered that the braze actually looked excellent. The pump went back in the car and worked perfectly for all the time I owned it.

The moral of this story is: just give it a try if you haven't much to lose. Sometimes one gets a useful surprise.

Ian P... I was confused by your comment initially but now I see that you are actually referring to the "Latest Posts" page. I was actually referring to the abbreviated list in small window on the right hand side of the main page that's entitled "Latest Forum Posts". I suppose I should set the proper "Latest Post" page as my favourite.

Gerry

Totally agree with the last one..... When new posts come in thick and fast, a particularly interesting one can slip off the 'Latest Posts' list never to be seen again unless one digs deeper. Apart from the nuisance factor to oneself, new posters probably don't get the replies that they are due. Make it bigger please

Gerry

Yes go for it ! It's a well thought out design.

The only advice I would give you is to make sure you understand how it all goes together before starting and get to know what's a flexible dimension and what is not.

I'm working on this clock at the moment but before cutting metal, or even buying metal, I've decided to create a full assembly drawing so that the whole design is clear in my mind. I don't plan to spend time on matching the exact form sketched out by Wilding so my drawing allows me to see quickly how I can modify, cut corners, save some cash or time. I did see a video somewhere where the builder bought some oversize brass for the front and rear frames then proceeded to cut slices off each with a slitting saw just in order to meet some arbitrary dimension in the plans. I really don't want to make work for myself doing things like this. Life is short enough as it is !

I also plan to metricate all the components to make life easier. I don't know about you but I find it increasingly difficult to decide quickly whether 27/64ths is bigger or smaller than 10/16ths, and by how much ! There are endless conundrums like this to contend with and plenty of opportunity in my case for mental aberations.

Gerry

oh yes, I'm also thinking of ditching the gears and going for timing belts instead. I know that will up set a lot of people but I like to explore crazy ideas sometimes.

Excellent to hear Robert, I never realised this was independent of speed ! Now I can check the efficiencies of some clock gear-trains and measure my improvements

Neil, thanks for clarifying that It reminds me of my ex-colleagues in Denmark that used to tell me that tube was flexible and pipe was rigid !!! All we need to do is get builders supplies catalogues on side and we'll all know what we are doing

….. and yes I have a smooth pipe ! Only issue was I drilled a hole with a 150mm core drill only to find that the standard "150mm" tube wouldn't fit through it. I had to use a 150mm sleeving which brought my bore down to 146mm ! Why do these plans always go wrong in the wrong direction instead in the right one ???!!!

Gerry

Hi Sandy, yes most cooker hoods are a complete disaster as far as noise goes. That why I started to build my own. With the top notch ones costing around £2000 I didn't think I could go too far wrong. But as its pointed out to me regularly " this has been going on for 3 years now. When will it be finished?".

There shouldn't be much direct vibration coming into the hood as the fan unit is now reasonably isolated on the outside wall. But the hood is a shockingly flimsy thing and it wouldn't take much to set it off, so the lumps of lead should take care of that. At the very least the lead will stop it sounding so 'cheap and narsty' when you press the buttons to switch it on, set the speed or turn the lights on.

But there is plenty of airborne white noise coming down the pipe and when that gets into the hood it will just bounce around and be focussed down to the cooker methinks. I'm hoping that the acoustic layer will take care of some of that. I probably need a to put a horizontal baffle in front of the exhaust port too, thinking about it.

This project is very much suck-it-and-see and with hindsight I should have perhaps gone for an even bigger fan but as they say, experience is all about mistakes. I could still come back to that later when I run out of things to do!

Adrians acoustic sheeting is 'said' to be suitable for engine bays so hopefully it will have sufficient temperature resistance and the aluminised coating will make it cleanable to a degree. If not, I can rip it all out and think of something else.

Thanks for your comments chaps ! I have some lead sheet so I will place some of this in the centre of each panel and will cover over with some Adrian's acoustic sheeting. Perfect !

Dave it could never be too quiet, but sucking all the heat out of the house is a possibility! Initial tests show that on full speed any room door not properly closed is pulled open by 5 inches ! Its a good job my boiler is in the attic !

Gerry

Hi All,

I'm continuing to make improvements to my horrible 'Luxair' cooker hood. I have already moved the fan unit outside along with hopefully most of the noise and vibration. Now I want to reduce the structural vibrations of the oil-drum-of-a-hood. You can see it in the pics below:-

I was thinking of gluing some 3/16" plywood in to the insides to stiffen up the large surfaces. But I also like to try to absorb some of the higher frequencies coming through the airstream from the external fan. I suppose I could try drilling a million holes in the plywood but if I can buy some stick-on material that has a proven effectiveness I think I'd prefer to go this route to save time. (I'm already being warned that this job is taking too long )

So, does any one have any experience of a stick-on material that will stop panel vibration, acoustically absorb and is obtainable in a 'domestic' quantity please ? mmmm ...as I write I'm thinking such a thing might quickly get clogged with grease....

Hi team,

I will be making a shaft around 6mm diameter and around 130mm long. To keep the weight down I'm thinking of drilling out the centre but as we all know drills can wander off line. I can attempt to minimise this with a good quality drill, a good headstock~tailstock alignment, good collets and with lots of pecks.

With say a 3 or 4mm drill, how deep do you think I could sensibly go ? I'm not worried about the strength of the shaft, a little about eccentricity but more drill breakage.

Gerry

oops, when I referred to 'extrusions' I did of course mean 'pultrusions' ! I was involved in some discussion on rubber parts just before I wrote my reply and the wrong term was clearly still stuck in my mind.

John, yes my rod is solid 8mm by 5mm, and I have been pondering the connections. I constantly wrestle with functionality versus appearance. A cnc-made elliptical hole would be the most elegant solution, with ugliest being a press-fit into an epoxy-filled circular hole. I did wonder if I could carefully drill the rod along its axis and glue something in this hole but these pultrusions split like a banana with very little encouragement when given any significant internal pressure. I might need to do a trial or two on this idea first.

I'm planning an elliptical pendulum bob too, filled scraps of tungsten, not to match the rod but to minimise drag of course. I might bond the rod directly into this then I only have one connection to worry about at the top.

I'm in no rush to decide these details just yet as there are just so many things to think about. By the time it's finished this clock will bear about as much resemblance to JW's small tower clock as I do to Donald Trump.

Gerry

John, I'm pleased you asked this question ! For my project (Wildings small tower clock) I have purchased some elliptical section CF rod with the aim of maximising the Q. Sadly this elliptical rod was only available in extruded form and I know from previous experiences that extrusions don't always drill well. In extruded form the fibres are all aligned so it has great strength but not much in the other. And there is very little resin separating the fibres. So it tends to get torn where the drill cutting edges move at right angles to the grain direction.

Of course, a lot depends on what quality of hole you are looking to achieve. A sharp carbide drill running at the highest speed with minimum force might give you a good enough result. But although I haven't tried it myself yet, a diamond burr, as suggested by Versaboss, would probably be even better as a diamond burr doesn't have one big ugly cutting edge.

Epoxies work well on CF extrusions which have almost no resin on the surface, (or in the material for that matter) so the glue can get right onto the fibres. I think I would be inclined to try put some epoxy in bore and on the outside surface you intend to drill to minimise tearing.

Personally I'm considering no drillings at all in my elliptical rod. I will bond metal fitting on to it and drill these. I'm hoping that metal parts will compensate for the small negative expansion coefficient of the extruded rod but I have to admit to not having done the sums yet

Gerry

Such things do exist ! Great. And now I know what they are correctly called I have been able to search more sensibly and I see even Cutwell advertise them. Thanks all for your assistance.

Howard, the plate is actually part of a small propeller hub. I'm actually building a balancer unit for it but didn't like the fact that the plate was a clearance fit on the mounting boss. This would lead to a loss of balance, not much if one does the maths, but I cant forget such things especially when it can so easily be mostly eliminated. The O-ring will allow assembly but help maintain concentricity until the bolts are tightened is probably the most elegant solution - in my mind at least .

Gerry

Hi MEs,

I have an aluminium plate 4.7mm thick and it has a 25mm dia hole in it. I would like to machine an O-ring groove (around 2 x2) in the bore of the 25 hole. What I imagine I need is a boring bar with a parting off bit coming off the bar at 90 degrees to its axis.

I don't have time to make such a beast - even self isolation wont give me enough time to do all the jobs I have to do - so I'd like to buy one. Thing is, I can find on any of the popular sites anyone selling the thing that resembles what I think I need !

Would anyone be able to point me in the correct direction ?

Gerry

Gary, I think I would agree with you. The saddle slope should be a reflection of the bed slope.

I suppose in using the saddle one could get some small 2nd order errors creeping in, but these should be negligible in my mind, and certainly no worse that putting blocks (which have their own inherent geometric errors) in slightly different positions each time one makes a measurement along the bed.

Gerry

Can the moderators correct the title so as we don't confuse people for the next ten thousand years ?