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By AES
#1200712
Thanks hawkeyefxr, glad you find it useful.

Re your one comment, you're quite right, you didn't read about releasing the tension on a hacksaw. I do on the band saw (for example), but have never done so on hacksaws. No reason why not, I just never thought of it, n was never taught it, but it obviously does make sense. Thanks - because of the extra tension on my hacksaw frames the bow IS becoming "a bit less/more bowed"! I shoulddo it.

AES
By AES
#1200914
@custard.

Thanks for the additional info about your job via PM. Sorry for my ignorance, but I now understand your scratch stock job - "a bit" anyway. (Being a dumbo, I 1st Googled "scratch block" which, apparently, has to do with coded jigsaws or something, nothing at all to do with wood working)!

OK, clear now. I'm lucky that my wife bought me a very nice scroll saw for my 70th, and personally I would use that with a suitable metal cutting blade for this job (you can down load a table of Pegas metal cutting blades from the link in my hack sawing piece - just under Photo 28). Pegas (amongst others) have blades tough enough and fine enough to cut your stuff OK. Then add a zero clearance insert to the machine and off you go.

If you don't have a scroll saw (it doesn't need to be a posh one, but MUST cut pretty slowly) then instead you could use the same blade in a Jewellers/Piercing saw frame if you've got one (the lower frame shown in Photo 14 - I think the other two frames shown in that photo probably wouldn't tension the blade well enough).

Otherwise I see only 2 choices, because neither the Goscut tool nor the Nibbler tool referred to in my post will, I think, do the job. At about Rockwell 50 your stock is a bit too hard/tough for both probably. So your 2 remaining choices I see are:

A thin cut off disc in a small drill: You don't need an expensive one - I've seen cheapos in Aldi or Lidl from time to time, and although my Workzone (Aldi) sounds a bit rough compared to my Dremel, it'll still do the job fine, OR;

A hacksaw with a 32 TPI blade: If going this route use an all-hard blade if possible, and set the job up horizontally, (flat) on the bench, not vertically in the vice.

If going the scroll saw or jeweller's saw route I don't think a "sandwich support" will be necessary (see below -PROVIDED the job is well supported below - hence zero clearance insert). 30 thou is not all that that thin in this regard. For lubrication ('cos I do NOT want "oil" all over my scroll saw!) I'd use a smear of Vaseline along each cut line.

But if you go either the cut off disc or the hacksaw route, then you'll need to set up a "cutting sandwich". Stale bread might do (!) but a piece of thin ply (up to say about an eighth inch thick, by no means critical, but STIFF) would be better - or even a scrap of thin mild steel or anything else you have to hand that's nice and stiff and not too thick.

Just as CHJ suggested in his previous post, the trick is to make a complete sandwich with a piece of support material under the job, plus another piece covering the top of the job. Do not use double sticky tape or similar between the laminations (it's too spongy). Just mark the job out on the outer face of the top lamination, then wrap the whole lot up TIGHTLY with transparent parcel tape. AND, as you cut each line, replace each of the now broken tape lines with another piece of tape top/bottom/over the cut before moving on to the next cut line. This will keep the whole assembly rigid without anything flapping in the breeze as you cut.

Lubrication is not necessary here IMO - cutting speed will be slow because you can't rush such a cut free hand, and anyway the lamination support pieces will act as a heat sink.

After the last cut, separate the sandwich - use a thin sharp knife and do NOT be tempted to lever the sandwich apart, otherwise you risk buckling the job.

You MAY have a very slight whiskery burr on the lower edge of each cut line, but this is easily removed by holding the job flat in your hand and gently applying a small smooth file, laying it ALMOST flat on the face of the job and gently stroking.

IF the cut line faces need a really fine finish before you file the profile/s into them, then set the job up in the vice (as low as possible) and use a smooth file in the draw filing method shown at Photo 27 in the files & filing post. Use chalk rubbed into the file teeth if necessary.

I don't know how often this job occurs in your shop custard, but I assume it's just "now and then". If so either/any of the above (two, or total four!) options should work without investing in anything more than scroll saw or hacksaw blades.

But if it's a "once a week job" (or more) then in your place I think I'd invest in something better - perhaps a sliding holder for a Dremel-size drill (or even a small angle grinder) to ensure dead straight lines with the cut off disc. A small thin cut off disc will definitely cut that stock - just don't let it get too hot.

I can't recommend specific angle grinder "holders" but if you follow the 1st link you'll find loads of pix of metal cutting stuff (in some cases they look big enough to cut up bits of scrap battleship)!

The 2nd link will take you to many pix, a few of which may ring a bell if you're considering the Dremel-size tools option. These include a couple of DIY holders that look easy to make. Again I can't recommend any specific products/plans because the bit of sheet cutting I do with cut off disc I do with a hand-held Dremel (or clone).

1st link:
https://www.google.ch/search?q=abrasive ... IqyJIook1M:

2nd link:
https://www.google.ch/search?q=mini+dri ... 93&bih=498

HTH.

But I stress I'm no expert and there are many other members with knowledge and experience, so it could well be that someone else will come up with better ideas.

Good luck.

AES
By graduate_owner
#1201182
Hey AES,
Firstly my handle - I have owned an old Myford ML8 for a number of years but never much liked the outboard turning, (possibly because I don't have the original parts) and had read that the graduate was the bees knees for turning. So when I saw a graduate bowl lathe going for silly money, I had to buy it. Then I searched for a handbook and came across this forum. Little did I realize how brilliant a forum it is, I just wanted some info on the lathe as a one- off query. Anyhow I was so pleased with getting the lathe that I used Graduate Owner as my one-off handle. If I had known how much use I was going to make of this forum I would have chosen a shorter handle !!!!

So, whilst my handle refers to the union graduate lathe ( you don't hate me yet, I assume), I do in fact have a Colchester lathe, a square head Master mark 2 - so now you can hate me. Just to go one further, I also have a floor standing vertical milling machine, and an Eagle surface grinder. I am ashamed to say, they don't get a lot of use. So now feel free to loathe and detest me to your heart's content.

Pity you are so far away. You would be welcome to come and play with them

K
By AES
#1201192
Thanks for the handle explanation g-o! :D

As I'm sure you realised (?), I was only joshing - truth is if I ever tried wood turning I think I'd get really hooked and that's definitely do NOT yet another "thing" to spend my non-existent time and money on! (hammer) (as applied by my long-suffering wife).

But I am jealous of all your metal working gear. Thanks for the "invitation" but these days I rarely get to UK (although my UK relations are almost all gone now) I have "promised" a road visit to a couple of Forum contacts, but my stupid back's not going to allow that any time soon, if ever. I remember only about 20 years ago, leaving Zurich early one Saturday morning in my little Escort, driving to just outside Cardiff to pick up an aero engine part, stopping for a few hours sleep in some hotel on the M4 early Sunday morn - it got foggy - and delivering the part back to ZRH by 8.00 on the Monday morning - quicker than courier, and no Customs formalities!

Those days are long gone unfortunately. My better half and I are off to the Black Forest for a week next week. It's only about a 2.5 hour drive (max) but regardless of if either she or I drive, it'll need one, probably 2 stops to "de-cramp" my back and legs!

But thanks, I appreciate it, you have a play for me instead (my little Chinese mini lathe is not bad, it just lacks rigidity). :D

AES
By AES
#1201213
Thanks mate. It's not very funny sometimes, but hey ho, I'm still alive!

At least when I can't do much in the shop I can (sometimes) sit at the PC and make long posts on the Forum (the last hacksaws thingy took over 2 months - NOT contiguously I hasten to add)! :D

AES
By Aden30mm
#1207263
A wise old Chief many years ago saw me struggling with cutting duralumin with tin snips. The secret he told me was to lock the bottom handle of the snips in a vice, and cut using pressure on the upper handle moving the material to detail the cut. For thicker section you can place a pipe over the tinsnips handle to increase the leverage. Please note in some circumstances power tooling was not available.

Nice thread AES (Aircraft Engineering Squadron)??

Rgs

Aden
By AES
#1207323
Hullo Aden 30mm. I know what those are (they were fitted to our Hunters, and later Lightnings) when I was on 1st line in the RAF - a WHILE ago now though!

Thanks for your positive comments.

I hadn't heard the tip from your wise old Chiefy before, thanks for that. Perhaps our Chiefys weren't as hairy "buttocked" and wise as yours!

Sorry to disappoint though - my AES handle is simply my initials (first, middle, family), nothing cleverer than that.

AES
By Silly_Billy
#1208111
If anyone needs a 1-handed hacksaw that works a treat, then I found the Milwaukee 48-22-0012 Compact Hacksaw is really excellent. The frame's rock solid and it's a quality tool. If Veritas made a junior hacksaw, this would be it.
Image
By AES
#1208123
Interesting Silly-Billy, thanks. Looks very similar to the one I pictured, but if it works OK (I'll take your word for it) then it's clearly a better effort than the one I pictured, which was, frankly, not very good.

I assume yours takes a standard 12 inch hacksaw blade?

Thanks for posting

AES
By Silly_Billy
#1208364
Hello AES - The Milwaukee 48-22-0012 comes with a 250mm blade. However, regular 300mm blades fit too. The blade slides right into the handle, so blade length isn't a big deal.

Whilst it's never going to cut the same as a 2-handed hacksaw, this Milwaukee's by far the best 1-handed hacksaw I've tried. As you mentioned in your original post, blade choice is crucial. Mine came with a 24 TPI blade. The Milwaukee blade was good quality, but not quite as good as the likes of Starrett. But you know more about blades than I do!
Last edited by Silly_Billy on 15 Feb 2018, 10:05, edited 1 time in total.
By memzey
#1228580
Hi Andy,

Great tutorial and many thanks for putting it up.

I went to my first car boot sale in ages today and with this post in the back of my mind, picked up the following:
Image

Are they the good ones you were referring to? The brands match but can’t make out if the red starrets are all hard or bi-metal. Also I didn’t realise Starrett made stuff in the UK - thought it was all US based production. Some of them are definitely unused while others may have done some very light cutting (can’t really see or feel any ware on the teeth but smudges on the side indicate some use).
By AES
#1228693
Hi memzey, good to "hear" you again.

Yes, AFAIK, Starrett do (or did, anyway) have a manufacturing plant in Scotland (in Cumbernauld I THINK, where a lot of US firms opened up in the 60s at the time of the UK "new towns" boom).

Taking the blades from the top (nice find BTW):

1. The top 3 are genuine Starrett "Red Stripe" brand "High Speed Steel" ("HSS" or "High Speed" throughout), NOT bi-metal. Along with "Eclipse" brand (James A Neil?) a VERY good brand IMO.

2. The Starrett "Green Stripe" blades are EITHER the "softened" HSS (to improve flexibility/reduce shattering on flexing), OR perhaps the lower carbon MS, hardened and tempered, I'm not sure. They are again NOT bimetal, and as per "my piece", will cut OK but not last as long as No.1 above.

3.The black "Eclipse" (along with the black one 2 below) are both unfamiliar to me (never seen those before). Note that they are both 14 TPI (a VERY useful find for cutting thicker stock) and are marked "all hard" which I take to mean that they're the "softer", (lower carbon MS) not HSS, but have been hardened to improve life but with reduced flexibility. I stress that this is a complete GUESS as I've never seen them before, but unless you can see a very faint "weld" line about 1 mil all along & above the teeth line, then they're not bi-metal (suggest bright light and a magnifier to check that last point - if it matters).

4. The blue "Eclipse" with the clear markings (between the 2 black blades), and the very bottom 2 "Eclipse" blades also (which show slight signs of having been used lightly, because the markings are just starting to wear away) are I'm pretty sure all the same, namely HSS, not bi-metal. So again, they can shatter if flexed or bent too much side to side. Again, somewhat rare these days I think as they're 14 TPI, so they're good for cutting "girt big slabs" of metal. The "all hard" markings, plus the "High Speed" indicates that these are, as said, HSS, which have NOT been "softened" to reduce the shatter possibility.

It's worth note that because those bottom 2 show signs of wear on the markings, they were probably used by someone who "knew his onions" (i.e. he used the full stroke of the saw), and the fact that there are 14 TPI blades in the mix indicates much the same (IMO). As does the lack of any bi-metal blades in that group, so either they were bought by the original owner some time back, before bi-metal (common as ditch water these days), OR that he knew enough about hack sawing that he didn't need to bother with the things, which like most compromises, are somewhat less than ideal!

None of the blades look worn out from you pix, and the HSS blades have lots of life left in them.

Just a word about "HSS" in case you don't know. Normal steel ("mild steel", "MS") has a low carbon content, so is not all that hard. This means that to make a decent cutting edge (not just on hacksaw blades), the steel was hardened and tempered after the cutting edge was formed. In industry, where time is money, this meant that if used at "high speed" (in a lathe for example), the tool got hot so that it quickly lost its hardened temper. So "HSS" was invented, which added more carbon. These tools are simply able to hold their hardened temper at higher temperatures, so allowing the lathe speed (example) to be higher without blunting the tool due to over heating. In our use, such as a hacksaw blade, where temperatures are (generally speaking) lower (!), this does NOT mean that the blade will cut any faster than a hardened and tempered ordinary MS blade - it just means that the HSS blade will hold its sharpness longer than. Later, special alloys such as chrome and cobalt etc, etc, were added to the basic HSS mix, and we're all familiar with things like socket sets being marked something like "Chrome Steel".

Diversion, sorry.

Hope the above helps, nice hack saw blade find :D