Good tool to cut perfect squares

[Riotvan88]

Hi guys 

 

Feel daft asking this but I need a tool to cut precise 90 degree cuts to make the blocks to fill my Hull. 

 

So far I bought a mitre box and saw I can make a square no problem but the saw has so much play that the cuts are never perfectly vertical.  

 

So for this reason I'm having trouble getting perfect filler blocks. I'm considering this 

 

https://www.drapertools.com/product/88192/550mm-Precision-Mitre-Saw

 

But it has mixed reviews on accuracy so. I thought I'd ask on here is there are any recommendations for a good tool to make very fine, precise cuts. Thanks 

[tkay11]

How about a table saw to its maximum height? You could probably do at least 25mm, and build up the blocks on top of one another -- although you wouldn't need to do it in heights that big.

 

Tony

[reklein]

Cut a little wide and use a disc sander to true up the angles.

[wefalck]

It also depends on what size of parts you are talking about ...

 

I have a mitre-saw like the one in your link and it works very well. For finer cuts I use a blade for metal. There is clearance in the middle to allow the blade to cut through, but this leads to the tendency of the blade breaking through at the last 0.5 mm or so. You can avoid this by placing a triangular piece of wood into the clearance. Also, clamp your stock to the saw.

 

Cleaning up will be required in any case. If you don't have a disk sander, you can make a sort of vertical hand sander from scrap wood. I think there are some examples here on the forum. Here is a picture of my micro-version to give you the idea:

 

 

[Jaager]

POB filling between moulds?  The material will be hidden.  It does not need to be pretty.  If there is a gap, use paper or cardboard to make up the short fall.  Liberal use of PVA will stiffen the paper. 

A right angle square, a piece of 1/2" plywood, and a sanding block will stand for a poor man's disk sander.

 

This particular tool has been said to be a Chinese copy of a domestic tool, that may have done in the original company.  It may look neat'o, cool'o  but a home made version will cost less and do what you want.   Tooth on the gluing surface is good, so 100/120/150 grit will cut fast and leave a surface for PVA to bond with.

[CPDDET]

I'm using a Japanese saw and a magnetic fence I made for it.

 

Using a machinist square to draw the angle.  Clamp the piece under the magnetic fence on my hold down table (made this myself as well). The fence holds the metal saw blade tight to it and the Japanese saw has zero kerf. 

[wefalck]

Sounds interesting, any image ?

[Gregory]

2 hours ago, CPDDET said:

...the Japanese saw has zero kerf. 

Is it invisible?  😄

[CPDDET]

Almost!

The kerf is the same width as the blade, .012 inches. Actually made to cut dowles flush and very flexible. Makes very fine cut. I have 2 Japanese pull saws as I only use hand tools for my build.

 

https://www.suizan.net/products/suizan-japanese-flush-cut-trim-saw-5-inch-hand-saw-for-hardwood-and-softwood

[CPDDET]

Wefalck:

 

What did you want images of? The saw? The hold down table? The magnetic fence?

 

Dave

[CPDDET]

Also use this saw for rip cuts. Have been able to cut 1/32 inch wide strips.

 

Does take some practice as these are pull saws, vs American saws that cut on the push.

 

The magnetic fence is a big help.

 

https://www.suizan.net/products/suizan-japanese-saw-6-dozuki-dovetail

Edited April 12, 2020 by CPDDET
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[wefalck]

I do know the Japanese saws, of course, ...

[CPDDET]

Just wondered what you wanted pictures of since I mentioned the hold down table and magnetic fence. 

 

Didn't mean to imply your knowledge of Japanese pull saws was lacking.

 

Always happy to share my novice techniques!

 

Dave

[CPDDET]

Hold down table, about 12 x 12. Three t-tracks and mini hold down clamps.

 

[gjdale]

6 hours ago, Riotvan88 said:

I need a tool to cut precise 90 degree cuts to make the blocks to fill my Hul

The only tools you really need are saw of suitable size, a square, a knife and a shooting board (which you can also make). Use the knife and square to mark your cut line on all four sides. Then saw just on the waste side of your cut line. Use a shooting board to clean up back to your knife line. You can use either a plane (best) or a sanding block on your shooting board to trim back to the knife line. 

 

You could also make your own mitre box by simply making an accurate cut with your saw part way through one piece of wood and then gluing/taping/screwing a second piece of wood to this as the platform/bed. Hold this in your vice and you have a mitre box with no play.

 

There are a number of videos on YouTube about these ideas. My favourites are those by Paul Sellers. Matt Estlea is also very good. Paul Sellers demonstrates making both a mitre box and a shooting board, as well as using and cutting to a knife line.

 

Edited April 12, 2020 by gjdale

[Thistle17]

It is not a coincidence that we all need a tool akin to those suggested here for all types of square cuts or even angle cuts. I made this simple one out of cut offs of MDF. It is modeled after my wood working shooting board. One can use either a low angle plane with a sharp, sharp blade or even sand paper glued to a stick. The plane is the Lee Valley Block plane. I am working on a similar version for angled fine tuning that will incorporate my mitre fence from my Byrnes sander.

Joe

Edited April 13, 2020 by Thistle17

[Riotvan88]

On 4/13/2020 at 1:08 PM, Thistle17 said:

It is not a coincidence that we all need a tool akin to those suggested here for all types of square cuts or even angle cuts. I made this simple one out of cut offs of MDF. It is modeled after my wood working shooting board. One can use either a low angle plane with a sharp, sharp blade or even sand paper glued to a stick. The plane is the Lee Valley Block plane. I am working on a similar version for angled fine tuning that will incorporate my mitre fence from my Byrnes sander.

Joe

Thanks for all the advice from everyone. Problem I'm having is I can't make anything with a 90 degree angle or flat face so if I try make those jigs it's pointless as they won't be straight themselves. I've tried planing a pice of wood flat to make a shooting board I can get the length straight but the thickness edge I can't get 90 degree it's always sloped. 

 

I've seen mixed reviews on disc sanders sub £250 price range and I'm not willing to spend that much.

 

On second thoughts I might try using a square on a base and a sanding block.  

Edited April 14, 2020 by Riotvan88

[Thistle17]

Practically speaking the only elements of the jig I suggest that need to be true are the : the shooting edge where the plane rides and the perpendicular placement of the cross piece or stop. This is easily accomplished with a square to align the pieces. Even a drafting square can help with the alignment.

Joe

 

[Bob Cleek]

3 hours ago, Riotvan88 said:

Problem I'm having is I can't make anything with a 90 degree angle or flat face so if I try make those jigs it's pointless as they won't be straight themselves. I've tried planing a piece of wood flat to make a shooting board I can get the length straight but the thickness edge I can't get 90 degree it's always sloped. 

A square is a very handy tool to have. Micro-Mark has a "thin-beam square" that I've found very handy for marking thin stock. The beam is thin, so it can be used on thin stock without having to put something beneath the stock to raise it enough that the arm lays flat on the stock. I don't know anybody who has this square but Micro-Mark, which isn't always the highest quality or the lowest priced stuff, but I have been very happy with this item.  It's twenty bucks, but it's one of those "loss leaders" they are always discounting if you sign up for their email advertisements. https://www.micromark.com/Thin-Beam-Square  Micro-Mark's set of 3", 4", and 5" small standard beam squares is a handy thing to have as well. These are also often discounted quite deeply on a regular basis. https://www.micromark.com/Steel-Machinists-Squares-Set-of-3

 

The two pictures at the bottom below show the thin-beam square on the left and a standard beam square on the right.

 

 

Planing a 90 degree edge is easily done if you lay the plane on its side on a flat surface. If need be, put something beneath the workpiece to raise it so the plane iron cuts the edge completely. Make sure your plane iron is set square to the plane's sole, of course. Use a square like those above for that as well. 

 

Edited April 14, 2020 by Bob Cleek

[CPDDET]

Here is another tool I find handy.

 

https://bridgecitytools.com/products/mini-miter-square?_pos=1&_sid=0f002990b&_ss=r

 

The edge plate is held on with magnets and can be raised, lowered or removed.

 

Dave

Edited April 15, 2020 by CPDDET
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[CPDDET]

Here is one more I have. Just 3 inches.

 

[Thistle17]

It is not uncommon to need to refine angle cuts. I wish I had thought of this jig when planking the gun pports of Cheerful.

 

Initially I had thought I would create another jig for the truing of angled cuts but after thinking that one jig might fit both applications and inspecting the commerical one shown earlier it struck me to make a small change to version 1.0. Version 1.1 utilizes the Byrnes sander mitre positioned as shown. I milled a 0.49 slot that yields a tight fit for the bar just deep enough to enable the mitre fence to sit flush with the jig surface. The slot is snug as I did not want the bar to wander into the trimming area. In this position one can trim just about any desired angle in either direction. I will modify the mitre fence by adding a wooden fence that will extend to the trim edge of the jig. I perceive it will need to be slidable to the trim edge especially if one chooses to use a low angle plane to prevent exit breakout.

Joe 

[Jaager]

https://www.stewmac.com/Luthier_Tools

StewMac is on the high side as far as price, but they have quality tools - if a bit specialized and limited their being focused on luthiers.   I have no association other than being a customer.

They also use email advertising - a lot.

 

Edited April 15, 2020 by Jaager

[iMustBeCrazy]

These days, factory produced mdf sheets come with four very square corners and four very straight sides. Even the smaller sheets.

 

To make the above shooting board, cut two rectangles from mdf each with 1 square corner and two straight edges (1 long and 1 short) stack and clamp the pieces aligning the long edges with the top piece set down from the top edge of the bottom piece. Fix a fix a stop piece across the top of the bottom piece using the top piece to keep it square. Unclamp. The bottom should now have a stop which is square to it's long edge.

 

Sounds really confusing but actually very easy once you grasp the idea.

[Riotvan88]

Thanks for all the advice. I've tried to make a shooting board. Very basic with the materials I have at hand as buying more wood is difficult now. 

 

I planed flat the edge of a strip of wood using a vice and a board I've then glued this onto an mdf board and added a stop to it. 

 

If this isn't precise enough I'll probably just buy a dedicated tool or a disc sander. Hopfuly when my mini planer arrives I'll be able to true up the edges for my bulkhead filler blocks. 

 

I did want to ask what exactly would be regarded as an acceptable tolerance for a wooden kit? I understand that no measure is ever perfect I'm an engineer in aerospace even a supersonic jet isn't 100% as per the drawing there's always a tolerance. I just hope my attempt at a shooting board is within an acceptable error. 

Edited April 17, 2020 by Riotvan88

[Bob Cleek]

1 hour ago, Riotvan88 said:

I did want to ask what exactly would be regarded as an acceptable tolerance for a wooden kit? I understand that no measure is ever perfect I'm an engineer in aerospace even a supersonic jet isn't 100% as per the drawing there's always a tolerance.

I'll bet you'll find your shooting board to serve its purpose well. Measurement tolerances with wood are not as exacting as with metal. Wood moves more than metal does with changes in ambient humidity. If it fits without looking loose, its plenty good for modeling. Remember the old saying, "Never send a rocket scientist to do a wood-butcher's job!"  

[Jaager]

Yellow PVA (e.g. Titebond II) has gap filling properties.  PVA fixed with wood flour from the same wood has even more. 

With the task of filling the outer perimeter gap between POB moulds - for to give support for planking and allow for needing only one layer:

Avoid Balsa at all costs. 

Basswood comes (or used to come) in packs of sheets 1/32 - 1/4" on line or from mega craft stores.  Easy to work but kinda dear on wallet damage.

Construction Pine from ~Home Depot or Lowes (Slows as my framing contractor in the Blue Grass called them)  2x4,  1x4, even thinner -easy to cut, soft put sturdy - avoid sap/resin stock.

 anyway, no one will see it,  so as long as it stays bonded in place, close enough is good enough.

If you paint, fillers take care of gaps.

If it is wood with clear finish,  as tight a tolerance as your skill allows.  If a piece does not measure up, toss it into a scrap box and start again.  You will know and you will always know if you just settle.  almost no one else will notice or know that it is less than perfect,  but you will.

editorial:

decks - make the caulking seams under scale and if the vessels is before 1860 - color it Walnut, not black  Drake's well was 1859.

Edited April 17, 2020 by Jaager

[Bob Cleek]

4 hours ago, Jaager said:

editorial:

decks - make the caulking seams under scale and if the vessels is before 1860 - color it Walnut, not black  Drake's well was 1859.

True in theory. In practice, once the tar got tracked all over the decks and dust and dirt and decomposed tow all mixed in, both the seams and the decks were black, unless it was a naval vessel or fancy packet with regularly holystoned decks. The tar would soften in the hot sun and get tracked everywhere.

[Thistle17]

In terms of accuracy don't let your engineering mind take you over the edge. That is my background as well and I know the feeling. From an accuracy standpoint I offer that you will be just fine. Keep in mind that there are very few rectilenear elements on a ship or boat as compared to a house. If you want to increase your accuracy beyond your adjustable square then treat yourself to a set of engineering squares (fixed blade, varied sizes). They are relatively cheap and they remove the variabiluty of your run of the mill adjustable version. I use them all the time in both woodworking and modeling.

Joe