Hemingway Hacksaw

[Mark Elen 1Participant @markelen1]

Ok, back on with the hacksaw build.

I made up a 5/8”BSF nut and the collet. I still need to slit the collet.

Cheers

Mark

Edited By Mark Elen 1 on 21/01/2019 21:58:39

[Mark Elen 1Participant @markelen1]

Tonight, I got the collet set up in a hex Stevenson’s block and sawed out the cuts. I got 90% done with the saw, the last bit I took out with a needle file.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

I got the collet finished, then bored the crank wheel to 10 degree included. Mounted the wheel on a piece of 11mm silver steel using the collet.

The casting comes with loads of 'meat' to remove to get to final dimension. Here it is when I first started on it:

and here it is coming into dimension:

I have got it marked up and ready to mill out the slot for the adjustable stroke, but have been mulling over ways of holding it for milling. I'm leaning towards making up some soft jaws out of ali to hold it in the milling vice. – it would probably be quicker to just bolt it down to the table….

Cheers

Mark

[Mark Elen 1Participant @markelen1]

I decided to make up a set of soft jaws to hold the crank wheel…..

I have cut up a piece of 1" aluminium to fit the vice jaws and a couple of shorter pieces to hold the 'proper soft jaws' in the correct position.

I also took my own advice, that I gave Ron a few weeks ago, and bought a SCLCL 12mm Left hand boring bar to fit the boring head.

I used a right hand bar, cut down to fit the boring head to take out as much as I could, then swapped to my new left hand bar. First thing I had to do with the bar, was cut it down to fit.

I have still got a way to go, the sides of the cut are great, but the bottom has a few ridge marks. I'm sure for this it wont matter much, but I am trying to think of ways to clean these up.

Thinking about it, these would probably been better set up on the Rotary Table and end milled out.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

I got to the limit of the boring head, as the head itself was going to hit the step on the soft jaws, so I changed over to the rotary table and end milled off the rest.

I also got started on one of the crank pins

And set it up in a square collet block to mill it down to 1/2” square for the crank wheel:

Cheers

Mark

[Mark Elen 1Participant @markelen1]

A bit more done today. I got the crank pin milled down to 1/2” square, then milled out the 1/2” slot in the crank wheel using a 8mm Ali slot drill. I finished off the corners very carefully using a needle file.

Cheers

Mark

[David George 1Participant @davidgeorge1]

Looking a very nice piece of work.

David

[Mark Elen 1Participant @markelen1]

Hi David,

Many thanks for your kind comments.

I have got a bit more done in the last few days. The con rod is complete, I reamed out the 1/2" hole and bored out the 5/8"

Then I decided to start work on the slide bar retainers. These took a bit of working out how to hold them as the castings were not square. I had to square up one side and make up a set of soft jaws to hold these whilst I worked on them.

The bosses for the screws didn't line up too well either. I decided to use the dro, line up centre on the raised portion on the back of the casting, then place the holes as best I could in the bosses.

The holes are correctly placed at 2" centres (50.8mm) but they don't line up in the bosses very well.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

One of the things that I have not been looking forward to was machining the bow. I don’t know why now. I got stuck into it last night, doing the slides first, then today I have set it up on the angle plate and drilled the boss.

Don’t look too closely at the spirit level on the square… I still need to level the mill.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

I got the hole drilled in the boss, then set back up on the table using the slide bar and clamps to hold the bow in correct alignment. I took really light cuts, because the bow is just hanging in free space.

I milled off the ends and the waste in the middle, made up the threaded adjuster, I need to mill half of the end off now and drill for the pin. I have marked up for the M5 screws to hold the blade, just need to drill and tap.

I have had to go 'off piste' with the adjuster screw, putting a 120 degree cone on the end. The drawings/casting is a bit out. the boss should be 1" long, but just skimming the end square, left it 3/4". I drilled down 39mm, the drawings called for 1 3/8" (34.93mm) even with this adjustment, if I had left the adjuster square and drilled for the pin at 1/4" the blade would not have fitted.

At 1/4" from the tip of the cone, the blade should fit with a little slack.

Cheers

Mark.

[Simon BirtParticipant @simonbirt51617]

Just fell across this. I built one of these last year it was an interesting project. It marked my return to model engineering after a nearly 20 year gap. Not sure if you have done it yet but the fit between the saw casting bearing surfaces and the arm that it runs on needs to be on the tight side. Mine makes a bit of a clunk when cutting as it changes direction. On reflection I would machine it within a few thou and then hand fit until it just slide on the bar. It was surprising how it loosened up jouring the running in process.

I’m very please overall, it cuts very well and is still on the original blade after 6 months.

Simon

[Simon BirtParticipant @simonbirt51617]

Here is a picture

[not done it yetParticipant @notdoneityet]

He he! If that pic is a recent one, you’ve not used it a lot_

Looks good, btw.

[Simon BirtParticipant @simonbirt51617]

It was taken after it was finished, it is now a bit less shiny, not sure if is appropriate to polish a hack saw.

[RuddxiParticipant @ruddxi]

I've decided im going to do this project myself and will be making an order very soon.

so i started searching for more info on the saw and found your build! very nicely done so far, and now i cant wait to get started myself!

[Mark Elen 1Participant @markelen1]

Hi Folks,

Many thanks for your comments. I have had a bit of time off this build. Lost interest a bit, but recently got the urge back to continue.

I have got quite a bit done but had the odd issue. The first thing I did was to sort out the riser for the vice. I had drilled and bored out for the vice screw as one of the first jobs I started with. Needless to say, they were miles out. I ended up making an aluminium block that was a good tight fit in the slide way of the riser that I could use to pick up the edges with an edge finder.

Before doing that, I set the riser up in the vice and ran a DTI down the slide way. Once I had picked up the centre, I bored the handle end until I had taken out the error, it ended up ~14mm

The other end wasn’t as bad, I managed to set it up the same and a 10mm endmill sorted it out.

I had to adjust the vice screw to my new dimensions. As I want the vice to operate the ‘right’ way, I got set up and screwcut a 1/2” BSF Left Hand thread, finishing it off with a die.

Next job was to set up and bore out the bottom brackets to 5/8”:

Then I got set up to make the drive shaft. This calls for a piece of 1/2” bar to be turned down to 11mm. I ummed and aaared as to how to set this up, but ended up with a small chunk in the 3 jaw and a live centre at the other. The first skim cut showed the tailstock being out of alignment. I had nearly .4mm difference over 5”. There followed a round of adjust, skim, mic, repeat until I got it down to .04mm

Done, in the mill and slot cut for key, key made and in, finished:

It ended up at 10.996mm one end and 10.992 the other. The hole in the gearbox is a touch under 11mm, as a piece of 11mm ground rod will not fit. (I bought it to save making this…..)

Cheers

Mark

[Mark Elen 1Participant @markelen1]

Hi Simon,

Thanks for the info on the slide bar. Mine is too tight. I ended up making some shims out of 4 layers of tin foil to allow it to slide. It is still fairly tight though. I may need to revisit this before it is finished.

Cheers

Mark

[Mark Elen 1Participant @markelen1]

I have tried….and failed to tap the vice slide. I bought a 1/2” BSF Left Hand HSS tap. I drilled out the cast iron to 11.1mm then had a real struggle to get the tap to start.

When it did, it felt like the tap was going to snap, so when it went ‘click’ I was fully expecting a tap in 2 bits. What I got was this:

Needless to say… there were a few swear words issued. There was a few hours work in that piece.

I’m now busy making a new one out of a piece of 50mm square cast that I bought this week. I’m wondering if I need to drill it out to 11.3 or 11.5 before I have another go, although, this time there will be plenty of meat around the hole, I will mill it back once the hole is tapped.

Pointers would be appreciated

Cheers

Mark

[not done it yetParticipant @notdoneityet]

One tap? Taper, 2nd or plug? Always a problem when only one tap is used.

I would likely rough it out on the lathe and only use the tap for finishing the thread.

Certainly cutting the thread before machining will help…

[Mark Elen 1Participant @markelen1]

Hi NDIY,

Taper Tap. I had a similar thought re roughing it out on the lathe, in fact I have bought a 55 degree 6mm internal hss tool. The problem is, the slide needs most of the machining doing, so that it can be held in place in the vice to get the hole in exactly the right place.

The other problem is that as the hole is only 11.1mm minor diameter, it needs a tiny internal threading tool. The part is 3/4 thick, so the tool is stuck out a long way in the tool holder. (Also, there is going to be a lot of very close up work to the Chuck. At least it is left hand, so all of the cutting will be going away and not towards the Chuck)

Cheers

Mark

Sorry, I have just clicked what you were saying re the tapping before machining. 
I will have a go at roughing it out on the lathe, once I get it machined down and the hole drilled. I can see a lot of hand winding of the tool back in coming…. I really need to get my hand winder that I have planned for the back of the lathe spindle made. 

Edited By Mark Elen 1 on 07/11/2019 19:55:22

[Mark Elen 1Participant @markelen1]

I have got on and remade the vice slide block. I had to set up the vice riser again in the mill to drill for the screw hole:

And here is the block I made that is a good tight fit in the slide, so that I could use an edge finder and the DRO to find centre:

I then clamped up the vice jaw with a couple of small .8mm aluminium shims to hold the jaw and block in place while I drilled out to 11.1mm. You can just see them poking out of each side of the jaw:

I then set it up in the 4 jaw and spent a long time getting the hole central on the lathe, followed by a lengthy set up of the change gears. The SC4 that I have would be OK for 16tpi right hand, but for left hand, the 120 gear hits the spacer in the gearbox when the 30 gear is swapped to reverse the lead screw. I ended up taking the spacer off, along with the woodruff key and holding the gear in place with a small washer that slid between the 120 and 127 gears. Not great, but usable.

After all that, the 6mm single point tool just sprang away from the hole and didn't touch it… Grr.

I ended up setting it up in the vice and tapping it by hand. It went better than last time, but not much.

Once that was done, it went back in the mill and I brought it down to finished size.

All in and done. The vice is a little tight, though not overly, I'm hoping it will bed in and slacken off a little with use:

Cheers

Mark

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