Double sided tape for router template?

[MusicMan]

Hi Musicman,
Glad to see you're getting back to it, hope all is OK with you. If you want, I can do you some more templates but put them on wider pieces of board with some slots that would allow adjustable side battens to be fitted and be wide enough that by using some threaded bar or clamps a base board could be fitted underneath and the whole lot tightened up to ensure position and prevent movement.

Just send me the dimensions (widest, narrowest and length) of the sound box and I'll make something up on the big SMC CNC. Oh, will need the ellipse radii for each of the holes again as I can't find the old pm. I do remember them each getting gradually smaller

That's another very kind offer. Let's see how I get on with the present ones and I'll come back to you if it is problematic. I can cut slots for clamps in these anyway, so they may be fine, and I never like to cause unnecessary work!

Thanks

Keith

 

[MusicMan]

Yes, that's the stuff. I'm happy to send you a sample first for you to try. Personally I'd be tempted to take Droog up on his very generous offer, a template you can cramp down will always be the least risky option.

Thanks again, yes I would indeed like a sample. I've PMed you my address.

I think there is enough scope to get clamps in my present templates and setup, so I will try after making wedges and cutting slots, but it is also very generous of Droogs.

I have had success using the clamps on the trial piece held in the vice. With just two clamps on one side, I first drilled and jigsawed out the bulk of the hole. At his stage I could easily get a cramp in to tighten the tape bond. Then I used a 12 mm straight 2-flute router with a bush slightly larger:

This left just enough to allow the final cut to clean it up. This was done by the same tool with the bearing follower. The clamps can be seen in this picture:

The accuracy was fine with just a little roughness where the cutter was rotating against the grain, and a small mouth of router burn thanks to my technique:

which cleaned up very nicely with a couple of minutes on the oscillating bobbin sander ... just what I bought it for!

The cut is now clean and smooth. The precise accuracy is not important; the idea was to get an elegant, smooth shape that looked right visually, which I think it is.

If I can find a copy router bit with a shear cut I think that would improve things, and some tape as well would give belt and braces.

Thanks all for your help. I'll keep you posted.

 

[Phil Pascoe]

If you are to invest in a shear cutter think about one with top and bottom bearings - it gives you the freedom to work something with the templet underneath - not relevant to what you're doing now, but who knows?

 

[MusicMan]

Thanks to Custard's very generous gift of Tesa tape, I've done the evaluation.

A short length of 25 mm tape was stuck onto the mdmd in a safe place:

The maple was placed on this:

then rollered down. I didn't try particularly hard to get it as flat as possible since I preferred to have a less-than-ideal specimen. It was then clamped in the vice for a few minutes:
Then the maple was pulled sideways (shearing the tape glue lines) using a heavy spring balance:

It came off at about 10 Kg force. Both surfaces were undamaged. The MRMDF was discoloured a little but the maple was not (it still has tape on the surface). A little sticky residue stayed on the maple in parts but was easily removed by finger rubbing and domestic Sticky Stuff remover.

That is quite adequate to hold stably while routing. I can't push that hard holding a router. So, two lengths of tape either side, plus two or three clamps for security should be fine.


Keith

 

[Droogs]

good luck and happy routing

 

[MusicMan]

Thanks, Droogs. One of the reasons I had such a long gap after you made the templates for me was that I got "trigger finger" problems in a finger on each hand, which meant that I couldn't hold many woodworking tools without making it worse, for several months. Happily, hand surgery corrected one hand and the other gradually ameliorated through physiotherapy. Fortunately I could still play the clarinet, that counted as good physio, but it's nice to be able to hold tools again!

cheers, Keith

 

[AndyT]

Interesting to see how a quality product gives good predictable results. Probably because I have only ever used unbranded double sided tape, I was thinking that there was a risk of spoiling the surface when removing it. I'm reminded that there's a lot of research into adhesives leading to some clever applications, such as self adhesive hooks which hold well but can be removed cleanly by stretching just the adhesive goo, at the correct angle.

 

[MusicMan]

Andy, that was my concern as well, but I'm reassured by the trial. You are right, there has been a massive amount of research in adhesives in the last few decades. Even metal airplanes and cars are held together with them (e.g. Lotus chassis, airliner panels). These, of course, have to be consistent. Tesa seem to me a serious company whose aim is to know everything about tape and produce appropriate products for the different applications. It will get a lot of use in my shop now.

Keith

 

[MusicMan]

If you are to invest in a shear cutter think about one with top and bottom bearings - it gives you the freedom to work something with the templet underneath - not relevant to what you're doing now, but who knows?

Good suggestion, Phil. After much search I settle on this up/down shear cutter from Wealden Tools, which they claim is unique. It looks ideal, so is worth waiting for.

https://www.wealdentool.com/acatalog/On ... m_871.html

I got distracted from the harp by an urgent bookcase build for the son!

Keith

 

[Phil Pascoe]

https://www.wealdentool.com/acatalog/On ... im_23.html
Is the one I've got, but yours is probably more versatile.

 

[MusicMan]

Ah yes, I looked at that one. On the task I have right now, I was concerned about the lower edge, which cannot be supported in my setup, chipping a bit under a down shear bit.I'll show how it goes (too cold for the shop right now!).

 

[custard]

If you are to invest in a shear cutter think about one with top and bottom bearings - it gives you the freedom to work something with the templet underneath - not relevant to what you're doing now, but who knows?

Good suggestion, Phil. After much search I settle on this up/down shear cutter from Wealden Tools, which they claim is unique. It looks ideal, so is worth waiting for.

https://www.wealdentool.com/acatalog/On ... m_871.html

I use those, like most Wealden tooling they're excellent.

Incidentally, using a shorter copy routing bit (rather than the standard kitchen fitters super long jobs), can be a lot safer when working on a template cut cramped to the edge of your bench.

 

[MusicMan]

If you are to invest in a shear cutter think about one with top and bottom bearings - it gives you the freedom to work something with the templet underneath - not relevant to what you're doing now, but who knows?

Good suggestion, Phil. After much search I settle on this up/down shear cutter from Wealden Tools, which they claim is unique. It looks ideal, so is worth waiting for.

https://www.wealdentool.com/acatalog/On ... m_871.html

I use those, like most Wealden tooling they're excellent.

Incidentally, using a shorter copy routing bit (rather than the standard kitchen fitters super long jobs), can be a lot safer when working on a template cut cramped to the edge of your bench.

Thanks, Custard. I have ordered the shortest one they do (30 mm).

 

[MusicMan]

OK finally the success story.

The up/down shear cutter from Wealden worked very well. After a delay caused by finding I didn't have an 8 mm collet for any of my 4 routers (!) I got one for the small Katsu router. I gave it a test run on a scrap piece of maple to get used to it. Then I taped up the work all round the hole using the excellent tape kindly sent by Custard, then was able to squeeze it all round from inside the rough hole, following advice by Andy to tighten it down well. I don't think it would have been stable without this. I then got cramps all the way round, and ditched any when needed to access different parts the hole (Custard again). So the ellipse was cut in parts and there was not a jot of movement of the template.

The three ellipses were cut in succession in a similar way. The templates made by Droogs worked perfectly. The templates were removed by using a wedge with a shallow taper, and there was no damage to either work or template.

And the final result was much to my satisfaction:

This is raw, without edge rounding or sanding and I am very pleased. Many thanks to Droogs, Custard and Andy for their help and advice. Well worth asking advice, taking it, and going slow!

I'll now go back to the harp build thread and pick up from here.

 

[Droogs]

How did this turn out Keith?

 

[peter-harrison]

Hi, these people do very nice router bits which I have used for similar work.
https://radiantools.com/

 

[MusicMan]

How did this turn out Keith?

The ellipse routing using your templates and the up/down shear cutter worked out really well. I then just rounded over the sharp edges and took the edge off the inside. Many thanks for your help.

The harp itself has not progressed much. The next step is sanding and French polishing the sound box and pillar/neck. Unfortunately, I contracted angina in the spring, which severely limited my mobility and workshop time till it was sorted out. I couldn't risk continuous activities even such as sanding (seriously) till it was diagnosed and sorted. The angiogram showed that I have ceramic arteries with a severe calcified restriction. Fortunately it could be fixed with a stent, but they had to blast the constriction with ultrasonics to crack it up before the stent could be inserted. Brilliant technology.

Anyway that has only just happened; I'm waiting for the final sign-off, but feel much better and beginning to do things again. Won't be long before I am back on the harp, and I'll report WIP as usual.

Cheers

Keith

 

[Droogs]

So sorry to hear about the problems, hopefully all sorted now and you can get back to the things you enjoy. I look forward to following the WIP, can't wait to see how it turns out. My other half is a storyteller and is kind of trying to persuade me to make her a lap harp kind of thing :roll: I want to find out how you get on first, hard, easy nigh on impossible bits first, to see if I'm willing to wast cash on trying it