MAKING BAND SAW BLADES

Stuart:

While John is discussing metal cutting bandsaw blades here, I am sure his observations also cross over directly to woodworking bandsaw blades

Originally posted on johnsmachines:

I have a band saw welder, but I find that blades joined with silver solder are more reliable.

The silver solder should contain at least 50% silver.

The jig below makes sure that the ends of the blade are held exactly correctly in position.

The blade ends need to be tapered at about 20 degrees to maximise the contact area to be soldered.

IMG_2589 The jig is held in a vice. The blade ends are held flat and against an edge which keeps them in line. The blade ends are scarfed at a 20 degree angle. The cap screws are finger tight.

IMG_2590 If you look closely you can see the scarf about to be soldered and joined. The edges to be joined are fluxed.

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MAKING STEAM ENGINES, CIRCA 1905

Stuart:

Some incredible photos of engineering from the turn of last century.

Incredible what engineers can make with seemingly inadequate technology

Originally posted on johnsmachines:

I am republishing these photos, which I spotted on the net recently. They show a factory in about 1905 making steam turbines for installation in a ship. The belt driven machinery, and factory scenes I found fascinating.  Their are also some pics of triple expansion marine engines.007_stitch_zps77e99731006_stitch_zps054b3bae005_stitch_zpsb3b28bf0003_stitch_zps1d5a5cdd002a_combined_zps3034921c001_stitch_zpsf052a758009_stitch_zpsc0136bc1004_stitch_zpsaa48624a006_stitch_zpscc231d7e

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A SawStop Rival

Bosch have released their equivalent to the SawStop contractor saw, with a version that does not damage the blade when it pulls it under the table.

It would be very interesting to do a side-by-side comparison to see if this compromises the reaction time of the saw, and whether there is any difference experienced in operator damage between the two.  I’m not convinced that saving the blade is the most important consideration, but it is an interesting bonus if there is otherwise no difference in the reaction time between the two systems, or amount of injury the operator incurs.

It would also be interesting to know what mechanism Bosch have used to actually detect flesh, and how that differs to SawStop.

How’s the weather?



A combination of American Walnut and Australian Merbau, with German weather gauges, finished with Danish Oil – a Celtic/Japanese fusion weather station.

The Torque CNC was awesome with how it was able to contribute to the project, with the aid of the Amana Tool 3D carving bits.  Very precise details, with a finish to match.

Got to use the Bridge City Kerf Maker as well when cutting the cross lap joints for the frame- awesome accuracy, and yet so easy to achieve.

Check out the full article on the build in the next edition of “The Shed” magazine.

Work in Progress

While I wanted to wait until the project was complete before showing it, I have just finished a mammoth step, so decided to share the progress.

Starting with a slab of American Walnut

DSC05827It has been resawn into two pieces, and joined together to create a slab of the required width

Then, after 24 hours of solid routing on the Torque CNC

DSC05838And a quick initial application of Danish Oil (as much to find where I need to do additional sanding), the result is starting to show some promise. (The gauges are only to test fit, they will not join the project until it is pretty much complete).  The top station (the celtic design within a circle) is not just decoration, it will also be a clock.  The gauges are all high quality German-made ones I bought from Carbatec.

DSC05849Exhausted getting this far, and I still have to have it finished by Sunday!!  And tomorrow is a day away from the shed :(

Big push at the end coming – how unusual………

On a mission

Sent the CNC router off on a bit of a job today, didn’t realise it was going to turn into such a mission!  

After a 4 hour roughing pass (which should have been a really big clue), I then gave the CNC the finishing pass program for a project I am currently working on.  Let’s just say that the rendering program isn’t very good at its time estimates. It thought about 9 hours would be about right.

In practice, the CNC has now been working for a solid 12 hours, has processed 1/2 a million lines of code (GCode, ie the instructions for where to go next in three dimensional space), and still has about 25% of the project to go!

Does go to show just what sort of workhorse the Torque CNC is!  

I’m sure that I could have made the job quicker if I had refined it better- learning curves and all that.

There has been one hiccup, and it is not the fault of the CNC, or the router bit.  Having the workpiece restrained to the table for such a long time, through the heat of the day, it tried to expand.  And couldn’t.  So it bowed a bit on one side, causing the router bit to dig deeper than it should, and has created a bit of a groove.

Fortunately I caught it pretty early on, and was able to fix the bowing so it could go back to cutting to the right depth.  Now. I just have to figure out how to fix the groove, or disguise it.  Learning curves!

You do waste a lot of time with a CNC- damn thing is mesmorising!  So cool.

The current job is one where I am amalgamating the CNC routered work with other components- using the CNC as one of the workshop tools, rather than a means to an end. Opens up all sorts of possibilities.

A logical conclusion

Using the same steps discussed in the last entry, I have taken a vector drawing of a Celtic Cross (created by “CarveOne” on the Vectric Forum), and produced a 3d rendering of the design.

This is the first time I have really tried using multiple paths on the same object.

The first pass was a roughing pass – used to remove as much of the unwanted timber as possible with a strong router bit, and higher feed rates to perform the task quickly.

DSC05816For this I used the 46294 3D carving bit from Toolstoday.com  It has a Zirconium Nitride (ZrN) ceramic coating, so this bit is also appropriate for routing in aluminium, brass, copper, cast iron and titanium alloy.  It makes very short work of the camphor laurel!

DSC05818There wasn’t a lot of material that needed to be removed, but it is still a worthwhile step to minimise any unnecessary load on the finishing step (and router bit).

DSC05820The final design was then carved using the 46282 3D carving bit.  This has a 1/16″ diameter tip, so can really get into the details.  Even so, there is a bit that is even finer, if even more detail is required (with a 1/32″ round nose tip).

I was using these at around 80mm/sec.

Once the design was cut, I swapped over to a solid carbide 1/8″ upcut bit to first cut around where the gaps were meant to be inside the design, and then to cut around the outside, down to about 12mm deep.

DSC05822For a sense of scale, the cross is about 300mm high, and 200mm wide.  Straight off the router bits, there is no need for sanding where the carving bits have been.  There is a bit of feathering on the outside of the cut out, but that is both a function of the timber, and insufficient router bit speed.

I deliberately didn’t cut all the way through the timber, so there was no need for tabs to hold the cut pieces in place.

To release the cross from the surrounding material, I turned the whole thing over, then ran a basic flattening profile on the back, taking off 2mm at a time with a surfacing cutter – using the RC2248 replaceable tip cutter.

DSC05825

Once this cut down to the required depth, the cross was released.

Each project presents different challenges, so I get to know more and more about how to use the CNC router effectively, and how to incorporate it as another workshop tool.

I had a look back at some tests I did on the CNC Shark using 3D carving bits – the finish I am achieving here is chalk and cheese compared to my early experiments.  I don’t know if I can attribute it all to the platform, but having such a solid, heavy duty CNC router certainly is not harming the finish that I can now produce!

 

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