How do you cut a really thin and deep slot?

[builderchad]

I am in the planning stages of making a frame saw and have recieved my blade and blade holders from Dieter Schmid (http://www.fine-tools.com/gestell.htm). The holders are 2.6mm thick so I need to cut a slot in the saw arms of about 2.8mm as I dont want them to move about too much.

My smallest router bit is 1/8" which is just too wide and wouldn't have the depth to go through the saw arm anyway. I can't cut the arms in half to make recesses as that would compromise the strength of the saw. Using a jewellers saw seems like a possibilty but I can see myself making a real mess of that :shock:. Besides I would need to start it with a 2.5mm wood drill bit and have not found any long enough as the thickness could end up being just under 2 inches. And I guess that a long bit at that length would wander a **** of a lot even on a drill press. Taking that thickness down is an option if I can't find a way of cutting this slot.

Are there any fairly simple methods for cutting thin slots (or through mortices I guess??)?

 

[SketchUp Guru]

How about laminating up three layers or even two? If you laminate three layers, you just leave a gap and if two, cut a shallow dado in both pieces before gluing.

 

[engineer one]

not sure i understand why you think that laminating the wood would make it any less strong??? :?

in principle the whole idea of a frame saw is surely that it is in tension when in use, thus the strength is maintained.

looking again at the site that you linked to, the frame saw has three horizontal elements, the blade, the centre support/pivot, and the tightening mechanism, in some ways, all the side pieces do is support these three,
therefore to me, laminating them seems a logical step for the blade support, also you can actually make this a more elegant and strong shape, by beefing up the pivot points, whilst making the rest slimmer, more resilient and more attractive.

the other way to go is do what is done on a hack saw for instance, and mount the blade supports on the outside, you will increase the bending moment slightly, but not enough i would venture to have any impact on
what you are doing.

in my distant memory, i seem to think that the biggest problem with a frame saw is making sure that you keep it vertical, and let the saw blade do the work, much more than with a normal hand saw.

not sure if this helps but it is another way of looking out of the box.
paul :wink:

 

[Colin C]

You can get long drill bits to do this and it can also be done on a drill press, you just have to take it slowly when drilling.
You could also make the drill a brad bit ( try Tilgear for one on the drill number is 01707 873434), if you dont know how I can show you , it is very easy

 

[Alf]

Could you not saw a slot and then glue in a suitable thickness of stock to fill in the open edge? Very strong I would have thought. Failing that, how about a really thin mortise chisel (B1)? :wink:

Cheers, Alf

 

[Scrit]

A bandsaw, the bigger the better, with a very fine set blade and the rtension cranked right up. , or failing that a mitre saw such as the Nobex Champion

Scrit

 

[builderchad]

Oops, forgot to point out that I am not making the same style frame saw as on the site. My frame saw has the blade in the middle position like this one:

I will also add two fences to my design to push up against each side of the board and keep the blade aligned. So there will be need to be runners or some sort of locking mechanism for the fences as well so I guess laminating will give me a lot more options for the fence fastening though I've never done laminating before.

Thanks for the Tilgear info Colin, I was also looking something harder than the usual silver steel and threaded bar you get at places like screwfix and discovered drill rods were harder but didn't know where to find them.

The 3/32" chisel from that site looks like the ticket if I go that way, thanks Alf.

 

[Alf]

Opps, shoulda said - my site, affiliation etc etc. Just a cheeky link really.

My reaction would be make the framesaw by slotting some threaded rod to hold the blade and use the blade holders for a more "continental" style frame saw. An easy matter to bore the hole for round blade holders. :wink:

Cheers, Alf

 

[builderchad]

Opps, shoulda said - my site, affiliation etc etc. Just a cheeky link really.

My reaction would be make the framesaw by slotting some threaded rod to hold the blade and use the blade holders for a more "continental" style frame saw. An easy matter to bore the hole for round blade holders. :wink:

Cheers, Alf

I was hoping to avoid that because the blade I have is 40mm wide and the holders that came with it have a large surface area giving the blade good support. I imagined that using M8 or M6 rod would mean the blade would wobble around more tilting left or right having a greater chance of going off track (esp. in untrained hands like mine ).

I am using the rod solution for my bowsaw which is ideal as it only has to hold onto coping saw blades.

 

[Alf]

One option might be to provide a slot for the blade a bit like on this one. The other is to glue a couple of blocks on the insides of the cross members as "cheeks" either side of the blade. I know there's an example of that out there somewhere but blessed if I can find it.

Cheers, Alf

 

[Scrit]

I was also looking something harder than the usual silver steel and threaded bar you get at places like screwfix and discovered drill rods were harder but didn't know where to find them.

About 30 years ago I worked for one of the Swedish steel producers. We used to supply STD (Sheffield Twist Drill) and Cleveland Twist Drill with drill rod ready dimensioned (i.e. ground to exact drill size). The material was mainly M2 and M42 HSS with the occasional order for something more exotic like ASP30 or ASP60. Even if you get this stuff it will need to be hardened and tempered in some way as the rod is generally supplied in annealed state. Oh yes, and ay decent steel stockholder or engineer's suppliers should be able to help - you'll probably find that they're cheaper, too.

Scrit

 

[builderchad]

Brilliant link Alf that is a very nice looking solution, thanks!

I'll stick to the standard rods from B&Q Scrit seeing as I have no way of hardening this stuff - SWMBO wouldn't approve of gas tourches in the shed. Guess it doesn't really matter seeing as the standard stuff is probably more than sufficient - just being a perfectionist