Member postings for Frank Gorse

I believe it’s also called di-hydrogen monoxide which sounds very nasty.

What this thread is short of is a bit of pedantry so may I point out that it’s only an acronym if the letters form a word,such as UNESCO,RADAR etc. Otherwise it’s just a TFLA (three or four letter abbreviation) You’re welcome.

Oh dear,

I am well aware that the three point fix by hand bearing compass was,and probably still is,the basic position fixing technique in traditional coastal navigation. But when I did the course at the local tech in 1980-something we also covered running fixes,doubling the angle off the bow,and other arcane stuff I can’t remember now. I’m not sure whether hsa’s were mentioned,probably not.

However,in ’Yachtmaster’ by Langley-Price and Ouvry,published by Adlard Coles,covering the RYA syllabus we read:

“If the sextant is turned so that it is held horizontally,it can be used to measure the angle subtended at the observer between two shore objects. A distance off is not obtained...........but a position circle can be plotted. Two such circles can be obtained from three landmarks,where they intersect is the fix.”

Quite right.one horizontal angle needs a compass bearing to give position. Two horizontal sextant angles on three objects gives a fix where the two arcs overlap and both were still in the textbooks for RYA yachtmaster not that long ago but I’ve never tried either.and shouldn’t want to have to when it really mattered.

There used to be tables of ‘dipping distances’ in Reeds (along with useful things like emergency childbirth) and I still have a copy somewhere.

Fully agree about GPS though!

Neil,that sounds like a pelorus,a simple horizontal protractor with a sight that is probably still fitted on ships today. Anything which relies on a spirit level is of limited use at sea but the horizontal angle between two known points will give you ‘distance off’,add a third point and you have a position fix. The same thing can be done with a sextant used on its side. No trig required,just a couple of lines on the chart but as you say you do need to be able to see the coast.

Or google “elforin”,sorry,don’t know how to do link.

Just to confuse things a little further,my 2b is about 63.5” with the vertical head on. Haven’t got the raising block yet but that will increase it by about 3.5”(made from 4x4 aluminium). My cabinet base is the steel version so that may account for the difference. Being quite tall I’ve stood my machine on timber bearers to bring it up to a more comfortable working height.

Not sure whether you’re talking about the mortice or just the shallow recess for the plate. As Jason says you’ll need to find a long bit and a decent router to do the mortice. Doing it by hand needs proper tools and if you had those you wouldn’t be asking the question. One piece of advice though, never “climb mill” with a router.

Do have a look at Ultra High Molecular Weight Polyethylene. I used it for a job on our ‘Westerly Something’. It’s even less affected by moisture than delrin,has similar frictional properties to ptfe and is very hard wearing. It’s also quite cheap.

Delrin,or acetal which is similar but not the same,has far less water absorption/swelling problems than nylon and has long been used for such things. Or try UHMWPE,even less absorbent and the frictional properties of teflon but slightly more trouble to machine than delrin.

Direct Plastics’ website has lots of info and they give a good service-usual disclaimer.

I didn’t exactly say I’d hammered them in! I was trying to take out the huge amount of endfloat on the existing bearings. The adjusting nuts on the spindle had no effect so I made a clamping plate,a close fit on the spindle to press on the spacing sleeve. With that fully tightened and beginning to bow I applied a tap-soft hammer-to the other end of the spindle which had the desired effect of unsticking the inner race from the spindle-no impact to the actual bearing at all. I don’t know what preload means in this context but I’ve finished up with no end float and no tightness.

What are you making your raising block from and are you going to make it on the Centec?

Yes,definitely the long version for all the reasons you say. I hadn’t really thought about the composite approach but I will consider it.If I can get the top and bottom surfaces parallel to one another I think I’ll be half way there,if I can’t it’s time to get professional help

Thanks for that chaps. I changed the oil when I first bought the machine and was amazed by how clean it was- I doubt that the previous owner had ever changed it- and the bearings looked perfectly ok so far as I could see. So I tried a bit more force. I’d already made a clamping arrangement with 2 lengths of M10 studding and now added,dare I say it,a few sharp taps with a hammer. Lo and behold,barely perceptible end float and it turns as sweetly as can be.

As for the proposed raising block the cheapest supplier I’ve found so far is about £94 inc vat and delivery so I’ll probably order that fairly shortly. I have an old toolmaker friend who will be getting a call if-when-I get stuck. The sensible thing would be to ask him to do it anyway but I’m hardly likely to start doing the sensible thing after all these years.

Frank

Well,I’ve taken the excellent advice about my raising block question and will be ordering a block of aluminium. By using a fairly big flycutter it should be possible to do each surface at one setting,the dovetails are another matter.

In the meantime I set out to investigate a bit of looseness in the main (horizontal milling) spindle. I’ve tightened up the adjusting nuts on the back as the handbook says but there is still almost a sixteenth (1.5mm) of end float when the overarm is removed and some radial play depending on which way it is loaded. I’ve now taken off the locknuts,pulley,sleeve and the plates back and front which are retained by four screws. I’ve also drained the gearbox and removed the covers to get a better view but am at a loss as to how to remove the spindle and bearings for inspection. Can anyone out there help please?

Presumably having done all this it would be sensible to replace the bearings in any case,can anyone recommend a helpful supplier?

Somebody suggested drilling and reaming for a taper pin through the round bit to ease the business of resetting after the head has been tilted,can’t see why that wouldn’t work but I haven’t done it (yet.)

Paul,Gary, Dave,

yes,the ability to use either mode of milling without troubling the local crane hire firm was the original motivation. Extra capacity is a welcome bonus of course.

Thanks to all for your input. Gary it was your post that I remember seeing some while ago, I hadn’t realised they were made of aluminium ,which would make the milling a bit less daunting,but still unfortunately too long to make on the machine itself and I don’t have access to a bigger one. One advantage of my original plan was that the dovetail on top need not be the whole length,just enough to park the VH so 14” or so would be fine. However that suggestion doesn’t seem to have found much favour!

Thanks for that Paul,mild steel is another option of course. Part of my plan was to reduce the amount of dovetailing to be done,milling is still something of an adventure for me! I do like your independant motor on the vertical head.

Nigel and Nicholas,thank you both for your comments but I fear we are at cross purposes. The photo on Tony Griffiths’ website shows a raising block the same length as the overarm with the vertical head permanently mounted on it so the horizontal facility is unaffected (though not increased ). My plan was to stick the VH on top of the overarm so as to have both available without any heavy lifting,the increased capacity in vertical mode being a welcome bonus.

However I take your point about modifying original parts. Anyone out there got a spare overarm they’d like to sell?

Martin,thank you but the part I need is specific to the machine I have which has not been made for many years.

Jon,thanks,I’ll have to open a yahoo account