8" Mini Shear/Brake

[Dr PR]

I recently purchased an small 8" metal cutter (shear) and bender (brake). I will be making several complex pieces of minesweeping gear from brass on my MSI build, and if I ever finish my CLG model it will have a number of complex brass assemblies. So I need to be able to cut and bend thin brass parts.

 

This is one of those Chinese made tools that is soled by several companies in different colors. The one I got is made by Kaka Industrial. Not a good choice of company names. According to the font of all knowledge, Google, "Kaka means poop in many unrelated languages." Time will tell if this thing lives up to its name!

 

I have had it only a couple of days and have just used it to test cutting and bending. So this is just an initial impression. But it appears to be a pretty well made tool with very few shortcomings.

 

It looks like a tool that was sold by Micro-Mark several years ago. There are also 12" shear/brake/roller tools available for about the same cost, but they weigh 70 pounds (30.5 kg) and would be hard to move around. This 8" shear weighs 28 pounds (12.24 kg) and isn't too heavy to carry around. I got this on Amazon with free shipping for US$264. The same machine can be had for about US$70-80 less, but with about that much shipping costs.

 

The photo shows what you get for your money.

 

 

The instruction manual is well written in very good English. However, it is pretty sketchy. The "assembly instructions"  do not tell how to assemble or adjust the machine. But from videos on YouTube I figured out how to put it together. I have used much larger shear/brakes so I had some idea how to adjust it. You get the large cast iron frame and most of the mechanism assembled. But you have to install the stops (see below) and bolt it to a bench top with the supplied four large bolts. Allen wrenches are supplied for adjustments and changing the cutter and brake (bender) tools.

 

The only real problem I encountered was large gobs of dried paint up to 1/16 inch thick (1.5 mm) on the bottom mounting surface of the cast metal part. When placed on a flat surface the machine rocked back and forth. But a large rasp removed this quickly. I also adjusted the cutter blades a bit to make for smoother operation (see below).

 

The instructions say it will work with materials up to the following thicknesses:

Aluminum                    1.2 mm

Copper                        1.0 mm

Brass                           1.0 mm

Tinplate sheet metal  1.0 mm

Circuit board              1.5 mm (Board thickness not specified. Board material not specified)

 

 

So how does it work? I tested it on 0.030 inch (0.76 mm), 0.015 inch (0.38 mm) and 0.0035 inch (0.089 mm) brass sheet, 0.009 inch (0.23 mm) galvanized steel, 0.008 (0.2 mm) inch tin/lead wine bottle seal, 0.003 inch (0.76 mm) printer paper and 0.001 inch (0.025 mm) tissue paper. It cut all with no problems, but the tissue paper cut was a bit ragged in places. I had to exert noticeable force on the lever only with the 0.03 inch brass, but it cut easily and cleanly.

 

The paper cuts and soft metal bottle seal cuts are especially noteworthy. The main fault I have found with other metal cutters is that the gap between blades and "slop" when moving is large enough that the soft material is just bent and between the blades and not cut. I really didn't expect it to cut the tissue paper, but it did a respectable job!

 

 

 

And it does bend to an enclosed (acute) angle of 60 degrees and 90 degrees (see below).

 

Here are some all around photos of the unit. The shear (cutter) is on top and the brake (bender) is below. The lever operates both - while the shear is cutting the brake is open, and vice versa.

 

 

 

 

 

The cutter has an upper "blade" and a lower "blade." Actually these are thick hard steel bars and not thin blades. The upper cutter is securely bolted to the cast metal frame. The lower cutter rises to make the cut. It is at a shallow angle to the upper cutter, so the material is not pinched between the cutters and forced to slide along the cutting edge, as happens with scissor-like tin shears and some other simple metal cutters.

 

The cut starts at the far side in this picture. This is the way the "big boy" industrial shears work. I have used 4 foot (1.2 meter) shears at work, but this is the smallest I have ever used.

 

The shear has a stop to allow repeated cuts at the same width. The stop moves with the lower cutter so the piece is supported during the cut. The material is fed from behind up to the stop.

 

 

The stop slides along the two rods and is locked in place with the two knurled thumbscrews. This is convenient, but the construction is loose enough to allow the stop to be positioned at an angle to the cutter (not parallel). So some care must be used to set up the stop before using it. Larger shears have spring loaded "fingers" that come down and clamp the work piece to prevent it from moving during the cut. This small machine does not have these, so I may have to hold the work piece manually.

 

Out of the box the two cutter blades were binding at one end. I loosened the adjusting screws and nuts and repositioned the upper cutter to just contact the lower cutter when it was raised. This was easy to do. The screws have locking nuts to fix them in position after the adjustments were made. This was pretty easy.

 

The upper cutter is a hard steel bar with a square cross section. This gives it four cutting edges. When one gets too much wear you just remove the four kex Allen screws on top with the Allen wrenches supplied with the tool and remove the top piece. Then you rotate the cutter 90 degrees, reinstall it, and replace the top piece.

 

The lower cutter can also be replaced. It is another heavy metal bar, but it looks like it can only be rotated once through 180 degrees to get one more cutting edge.

 

 

 

If I have any criticism for the cutter it is that the stop can be positioned no less than 0.276 inches (7 mm) from the cutting edge. So it can't be used to cut pieces less than 7 mm wide. But I used a piece of wood (metal, plastic, whatever) to close the gap to cut narrower pieces.

 

 

 

 

 

 

If you have access to machine tools you can easily make your own custom stop to allow narrower cuts without having to fiddle with the extra filler pieces.

 

The stop can be moved out to about 3.14 inches (80 mm) from the cut.

 

 

 

 

 

 

 

 

The brake has an upper tool with a "V" edge and a lower "prism" with a "V" notch. The material is fed from the front until it contacts the bending stop in the back. Then the lever is pulled down to form the bend. The stop can be positioned very close (~1 mm) from the back of the bending tool.

 

 

 

The machine comes with one 8 inch (200 mm) long tool and four shorter tools (1.57 inch/40 mm, 0.79 inch/20 mm, 0.59 inch/15 mm and 0.395 inch/10 mm). The shorter tools can be installed singly or in combinations up to 3.35 inches/85 mm). These can be used to make boxes and other complex bends.

 

 

 

The lower part of the break is the "prism." This is a metal bar with "V" grooves that the upper tools fit into to make the bend. The smaller groove makes 90 degree bends and the wider groove makes the 60 degree bends. This bar just slides in a channel at the bottom of the brake. To change the bend angle you pull the bar out, flip it over and slide it back into place. It is not bolted to the chassis. The bending stop slides on the two rods mounted on the back side of the prism.

 

 

 

The only other criticism I have at this time is the lever that operates the machine. It rotates through about 270 degrees, so the shear/brake must be mounted at the edge or corner of the bench. More expensive machines would have gears to operate the mechanism with a shorter lever throw. But this requires expensive gear sets, and can make it harder to cut (more force needed on the lever).

 

All in all it looks like a pretty well built and useful tool. After I use it a while I will post my more informed impressions.

 

PS: It comes with a "T-block" (seen in the first picture between the shear and brake stops). Can anyone tell me what this is for? It fits in the channel for the brake prism, so I suppose it can be used in some way for bending.

 

Edited Thursday at 05:30 AM by Dr PR

[Y.T.]

Amazing little machine. It has all major features of industrial full size machines.  

[kurtvd19]

I have the same tool bought 20 years ago from Micro-Mark.  My tool is red otherwise identical.  I have found  it to be the perfect size for my needs and it has been worth every penny I have invested in it - though I have no idea of how much I paid back then.

It has been altered to incorporate a micrometer feed for the shear.  It has an extension to enable very small strips to be cut.  I will get it out and take a few photos of it concentrating on the micrometer feed mechanism - might be a day or two till I get to it.

Kurt

[Dr PR]

Kurt,

 

Thanks. I will be making 1:48 scale strips and "L" pieces that are on the order of 3-6 inches across at 1:1 (1/16 to 1/8 inch at 1:48) so I need a good way to control the width.