Member postings for ChrisH

My 300 arrived on the 8th too - SHMBO got it out the post and just laid it on the side and never told me, was there two days before I found it - you just can't get staff these days

Why are the Chinese no good at cricket?

Because they eat all the bats........

Dave , Clive - The followers are not a problem as they are very straightforward, but point noted - obvious really!

The major worry is the cam ring which is literally a ring with the cams cut on top and a short flange on one end with M3 tapped holes for securing. The inside diameter of the ring is a sliding fit over the cam support piece, which is an aluminium piece running on ball races on the crankshaft (it rotates in the opposite way to the crankshaft) and also carries an internal gear.

I think I will get some case hardening powder in ready, but see if the finished cams work first before hardening. Then at least I will know if it needs a redesign or not, and if it does deform whilst case hardening I can approach the making of a replacement in a slightly different way.

Chris

Thanks Dave - sound advice from you as always

Chris

I am just making a cam ring for a model three cylinder radial aero engine. This is a new experience for me - first cam I've made! There are just two cams, an exhaust and an inlet, mounted closely together on a cam ring, diameter a tad over 2.5" diameter. The ring is a snug fit on a support piece. As it was a first attempt I made it out of EN1A, not ideal material maybe but given my record of making scrap parts and the likelihood of having to make it again probably a wise move.

In an ideal world the cam would be case hardened, and I would like to do that out of completeness, but again that would be a first for me, so a number of questions arise:

1. If the engine is not going to be used other than once or twice to prove it runs then is it worth it?

2. Will there be any growth in the cam rings as a result of case hardening, and is so, by how much?

3. Will the ring as a whole grow - I want it to still fit on it's support ring after?

4. Is there a way to case harden only the cams and not the rest of the ring? I did read somewhere recently about using fireclay or similar to protect tapped holes, would applying that to the whole of the area to be protected work?

5. Is it normal to case harden cam rings for model IC engines? That should have probably been the first question.

All things for me to ponder over the festive season, but if anyone has been there, done that and can offer thoughts and/or advice then it would be gratefully received.

In the meantime, Merry Christmas to one and all, keep safe

Chris

PS - a final question, how easy is the case hardeneing process?

Edited By ChrisH on 24/12/2020 12:42:23

Yes I did look at pevious threads but they were a while ago and I just wondered if anyone had some up to date experience of a modern one, seeing as how technology moves faster than one can keep up with! Thought perhaps the cheaper ones might have improved a bit, or the previously more expensive ones maybe come down in price.

Giving a brand and maybe a model number of a good one would be appreciated, but it needs not to be too expensive otherwise it gets hard to justify.

Chris

I have a number of small model engine bits and items that need cleaning and thought perhaps an ultrasonic cleaner would be jolly useful. So looked on-line and it appears Amazon do a number of cheap ultrasonic cleaners for under £50 and a few over £50 too.

Does anyone have any experience of buying and using one of these - are they any good?

All feedback welcome!

Chris

Just to complete this thread by an update - it would appear that I might now have just about cured the problem. Close examination showed that the top, or big end, of the taper was correct at 0.7" and that the problem seemed to be at the bottom - perhaps when the sleeve was fitted it closed in a tad at the bottom, who knows?

I obtained a MT2 "finishing" reamer from Chronos, ordered on Sunday, they took until yesterday to despatch but Royal Mail delivered it today. I have nearly finished reaming the bore, it's quite tough, but have marks now all the way up, quite a bit (relatively) taken off the bottom and now a new arbor with a 1.5" diameter soft top from Arc has a run out of just 0.001" - vast improvement, can just about live with that. Will complete over the weekend hopefully.

Chris

Jose - I haven't got a WM12 or WM14, but the basic rule of thumb of advice given to anyone buying a mill seems to be to buy the biggest and heaviest one you can afford to buy and have the space to fit in your workshop. With milling you need a machine as sturdy and strong as you can get!

Chris

My dear old Dad, long since passed away, got a pea shooter and some dried peas to 'discourage' the seagulls from nesting on his chimney stack. He didn't want to kill them, just to encourage them to find somewhere else to nest.

It didn't work very well, the seagulls stayed; I did suggest an air rifle might be more effective but as I say, he didn't want to kill them. What he would have made of todays nutty world gone mad I dread to think.

Chris

Thanks for the info Michael - you were quite right, I was unfamilar with the BCA , now all is much clearer!

Chris

Just a final thought for today - does anyone know how the MT bore is held in a HV4 rotary table, like is it a press fit, secured by adhesive, have a locking screw, whatever else comes to mind?

Chris

Thanks for that Oily Rag - will measure the taper mouth tomorrow as well.

Andrew, Old Mart - a parallel bore, now that has given me something else to think about. Quite like that idea, especially in the long term. Options, options, Guess what I will be thinking about as I go to sleep shortly!

Michael - I am not following your last paragraph, but it is late at night.

Chris

The taper in the RT is supposed to be M2 according to the spec but as NDIY deduces the taper is wrong, hence it only fitting at the bottom. As far as I can see, there is nothing protruding at the bottom and nothing impacted in the bore, it's clear as a mountain stream. I will test the bore is running true, test if the bore is hard, and if all is good then buy a reamer and give it a burst.

Chris

Huh, by the time I had posted my second post there were another three posts I've only just spotted - better read them now!!!

Chris

Peter - David, thanks for the prompt replies. I see Arc's M2 reamers are to HRC 60-62 which is encouraging! Might just tackle a hardish bore, but I will try a needle file test first as suggested. Needless to say I do not have a M2 reamer!!

I did clock the top of the RT, thinking it might have a slight list relative to the mill table, but it was spot-on. I didn't clock the bore but will do tomorrow - I do hope that it runs true, I don't fancy having to grind it true, for a start I haven't seen a grinding wheel on a long enough shaft to put in the Dremmel to get all the way down the bore. Don't fancy having to machine it with a carbide boring bar either for that matter.

Peter - are you suggesting one solution might be to replace the M2 socket in the RT ? - I hadn't thought of that one.

Chris

I have one of Warco's HV4 Rotary Tables which has not been greatly used in the 7+ years I have owned it. However, I want to use the table on an item about 2.5" diameter, held in a mandrel in an ER32 collect chuck. The collet chuck is screwed onto a fitting with a M2 Morse taper into the rotary table. The fitting was turned true in the lathe having been secured to a M2 blank end arbor fitted in a M2 to parallel adaptor and set up to run true, so I was sure this item was good.

Out of interest, having set up the part on the mandrel in the collet chuck on the table I clocked the part which I had just turned true with a DTI. It showed about 0.010" run out of true over the 360 degrees. Checking why, I put a brand new M2 blank end arbor from Arc with a 1.5" diameter end - this I reasoned should - must - run true, it didn't.

Then I found that although I had put the new arbor in the RT M2 taper securely (I thought!) there was slight movement on the top. 'Bluing' the new taper and trying it in the 'hole' showed that it fitted well at the bottom but was not touching at the top. I then tried it in a M2 to 1" parallel adaptor - perfect fit.

So the conclusion is that the M2 hole in the RT is not true and required remedial action.

My thought was to run a M2 reamer down the hole, but wondered if this would work, would the hole be too hard for the reamer, would the reamer ream true or at an angle?

I thought that if I centred the RT under the quill I could hold the reamer in the quill and gentle do it, which would hopefully make it ream true, but would the material being reamed be too hard?

Anyone been down this route? Any advice or thoughts other than using a reamer?

Chris

Had a scam phone call today, we were out but they left a message warning that our internet line was to be terminated in 24 hours as 'they' - whoever they were - had detected a hacking or similar incident on something, perhaps our IP address - who knows - and to contact BT press 5 and other press 9.

Just warning of yet another scam attempt.

Chris

Dan - my lathe is a Weiller LZ280, a quality German lathe from the late 1960's early 70's now well used but still in good condition/. Acquired it when a boat repair firm went bust nearly 20 years ago. Tool height from bed is 125mm, so bigger than a Myford!

I made 12 tool holders, not yet ground all the tools up to fit yet mind, adapted some holders to take a specific tool and otherwise standardised on 3/8" tool steel. The first 4 tool holders were made from a length of bright steel a bit bigger all round than the tool holder size but I saved some money by buying a 300mm length of black steel cutting it in half lengthways and making 8 tool holders from that machining a bit off all round. By planning the machining and machining all holders in pairs in stages one after the other I got all 8 holders exactly the same size. There are only a couple of crucial (measurement-wise) stages to do but by thinking the machining sequences through before starting and especially how I was to do the crucial bits the actual machining went quite quickly and and accurately and without drama.

Good luck.

Chris

PS - I have added a family photo in Albums

Edited By ChrisH on 09/12/2020 18:33:14

At last - a ray of sunshine in todays dank and dismal Somerset - No.299 arrived today!

Chris