Search found 705 matches

by peter.coombe
Sun Feb 12, 2023 10:45 am
Forum: Instrument Builders Forum
Topic: Shape of Braces - Is conical cross-section the best shape?
Replies: 13
Views: 6740

Re: Shape of Braces - Is conical cross-section the best shape?

As described above, you can reduce mass by making braces tall and thin, or drilling holes in them. However, carbon fiber has a very high stiffness to weight ratio, no wood even comes close, so the most effective way to make braces stiffer and lighter is to use carbon fiber tow. It is no coincidence ...
by peter.coombe
Sat Feb 04, 2023 11:18 am
Forum: Instrument Builders Forum
Topic: Shape of Braces - Is conical cross-section the best shape?
Replies: 13
Views: 6740

Re: Shape of Braces - Is conical cross-section the best shape?

The only really practical way to make an I beam brace is to use carbon fibre tow on the top and bottom of the brace. That is how falcate bracing is implemented and is very well covered in the Gore/Gilet books. As you say it does make braces that a lighter in weight for the same stiffness. If have no...
by peter.coombe
Wed Jan 04, 2023 11:00 am
Forum: Instrument Builders Forum
Topic: New Luthier Tips du Jour video - CNC and Lutherie
Replies: 5
Views: 6569

Re: New Luthier Tips du Jour video - CNC and Lutherie

I actually contacted Multicam and went as far as getting a quote on their smallest machine. Industrial quality machine, designed to run all day every day, weighs around 400kg. The offer was quite good, included delivery, installation and 6 weeks training course. However, to justify the cost I would ...
by peter.coombe
Tue Jan 03, 2023 11:09 am
Forum: Instrument Builders Forum
Topic: New Luthier Tips du Jour video - CNC and Lutherie
Replies: 5
Views: 6569

Re: New Luthier Tips du Jour video - CNC and Lutherie

Just 6 months ago I decided to get more serious about CNC (I had a small and very problematic Chinese machine bought to cut the "Coombe" headstock logo) and took advantage of the tax advantage that ended on 1st July 2022 and purchased a Stepcraft M700 with the ballscrew option and aluminum table. Se...
by peter.coombe
Mon Dec 19, 2022 1:35 pm
Forum: The Gallery
Topic: Tiger Myrtle OM
Replies: 5
Views: 14486

Re: Tiger Myrtle OM

Thanks. The inlay was done with my new workshop toy, a Stepcraft M700 CNC. It is Huon Pine and Blackwood. It took a while and a few iterations to get it right, but I do like the end result. That is just scratching the surface of what I can do now. All theoretical of course, it all takes time and exp...
by peter.coombe
Sat Dec 17, 2022 10:04 pm
Forum: The Gallery
Topic: Tiger Myrtle OM
Replies: 5
Views: 14486

Tiger Myrtle OM

Just finished. OM guitar in Adirondack Spruce and Tiger Myrtle. Bloodwood bindings, Blackwood bridge, African Mahogany neck, and Huon Pine rosette. Schertler tuners. I really like the wood combination of red bindings with the Myrtle and the Huon rosette. I love Myrtle. More of us should use it. I do...
by peter.coombe
Thu Nov 03, 2022 9:56 am
Forum: Instrument Builders Forum
Topic: New Luthier Tips du Jour video - Royal lac
Replies: 11
Views: 7717

Re: New Luthier Tips du Jour video - Royal lac

I got given a secret family recipe when I was in Canada a few years ago. Add 10% ea of Mastic and Gum Sandarac to your flakes when dissolving them. What all is liquid bring the mix to the boil for a few minutes, three times. Then let it cool, dilute and proceed as usual. This recipe also appears on...
by peter.coombe
Tue Nov 01, 2022 10:52 am
Forum: Instrument Builders Forum
Topic: New Luthier Tips du Jour video - Royal lac
Replies: 11
Views: 7717

Re: New Luthier Tips du Jour video - Royal lac

Not much good to us. LMI ships it to USA only.
by peter.coombe
Sun Aug 14, 2022 11:25 am
Forum: The Gallery
Topic: Early Romantic Stauffer style guitar
Replies: 6
Views: 13291

Re: Early Romantic Stauffer style guitar

Nicely done.
by peter.coombe
Wed Aug 03, 2022 10:01 am
Forum: Instrument Builders Forum
Topic: Epoxy, brushes, CF tow, oh my!
Replies: 10
Views: 6172

Re: Epoxy, brushes, CF tow, oh my!

I got my carbon fiber tow from http://carbonfiber.com.au/. There is enough in one roll to last me a lifetime. Note that 60m is still quite a small roll. I also bought some CF cloth at the same time, but that is still unused in the container. I have been using West Systems epoxy, and measure it out w...
by peter.coombe
Sun Mar 27, 2022 10:52 am
Forum: Instrument Builders Forum
Topic: Applying G&G techniques to a kit guitar
Replies: 14
Views: 8939

Re: Applying G&G techniques to a kit guitar

I have just done some modifications to a guitar I made just before reading the books, so your post is timely. I have been using it as a reference, but all my recent guitars beat it easily so it was not so useful as a reference any more. The first thing I would do is to add two blocks of wood with T ...
by peter.coombe
Fri Jan 21, 2022 10:27 am
Forum: Instrument Builders Forum
Topic: Resawing, Bandsaw drift etc
Replies: 10
Views: 9613

Re: Resawing, Bandsaw drift etc

Even with a properly set up saw, runout can cause drift, especially with hardwoods. If you orient the plank so the runout points away from the fence that can help reduce the drift. Other way around and the drift ends up cutting too thin and you have firewood. Is of course better to have no runout, b...
by peter.coombe
Tue Jan 18, 2022 10:45 am
Forum: Instrument Builders Forum
Topic: Red gum
Replies: 28
Views: 28634

Re: Red gum

You could try ripping up a few sleepers from a local railway line Ha ha, yes well I started woodworking with Jarrah reclaimed from the old Blackwood (in SA) railway station. Dad worked for the railways and when they demolished the wooden platform when I was about 10yo, he scored some hefty Jarrah p...
by peter.coombe
Mon Jan 17, 2022 12:00 pm
Forum: Instrument Builders Forum
Topic: Red gum
Replies: 28
Views: 28634

Re: Red gum

Yes I know about the impending ban on logging. I did find a quarter sawn plank of Jarrah in the wood stash that I had forgotten about so I am ok for a while. Mostly straight grain, but has good colour. In the meantime I have sourced some figured Jarrah and am waiting for them to get back to me. They...
by peter.coombe
Thu Jan 13, 2022 2:47 pm
Forum: Instrument Builders Forum
Topic: Red gum
Replies: 28
Views: 28634

Re: Red gum

Following on from this, I have made 2 more Red Gum mandolins, and they all sounded very similar. So the first Red Gum mandolin was not a fluke. All 3 sold quickly. I had some left over Jarrah from a bed I made around 30 years ago so thought I would give that a go. I made 2 Jarrah mandolins 27 years ...
by peter.coombe
Sat Nov 06, 2021 10:33 am
Forum: Instrument Builders Forum
Topic: Hello everyone and my first question
Replies: 7
Views: 9355

Re: Hello everyone and my first question

I get my logos done by Andy DePaul if I want it done in shell. These are all done by hand, not something I can do myself, the eyesight ain't what it used to be. I also have a small CNC that I use to make my logo out of wood. The CNC sounds like a good idea, but it was a great time sink until I got i...
by peter.coombe
Thu Oct 21, 2021 11:09 am
Forum: Instrument Builders Forum
Topic: US Postal Service
Replies: 9
Views: 6622

Re: US Postal Service

I have now got the tracking numbers for my tuners and tailpieces. The tuners have left LA, so they should be ok (phew). The tailpieces are still in the USA and appear to be stuck. Last entry was 3rd Sept, so that is a real concern especially since I have more than $800 invested in that package. Unfo...
by peter.coombe
Wed Oct 20, 2021 12:20 pm
Forum: Instrument Builders Forum
Topic: US Postal Service
Replies: 9
Views: 6622

Re: US Postal Service

Oh no. I have 4 sets of Rubner tuners and 4 James tailpieces sent via USPS, adding up to quite a bit of $$s. Both have been taking their time, which is normal at the moment. The Rubners bounced and they resent via USPS priority express post. I don't have tracking numbers (yet).
by peter.coombe
Mon Sep 20, 2021 10:20 am
Forum: Instrument Builders Forum
Topic: Bandsaw recommendations
Replies: 20
Views: 20935

Re: Bandsaw recommendations

I have an Inca, purchased from Garret Wade Melbourne in 1993, and as Nigel said it is a superb small bandsaw, especially with the Inca bandsaw blades. It did all my mandolin work and more for 16 years, and it is still doing it. Even re-sawed 2 Jarrah mandolin sets. Had to take it slow and careful, b...
by peter.coombe
Wed Jul 14, 2021 7:13 pm
Forum: The Gallery
Topic: New OM
Replies: 4
Views: 7086

Re: New OM

May I ask what finish protects this Mandolin pls?
Target Coatings EM2000.
by peter.coombe
Mon Jul 12, 2021 9:34 pm
Forum: The Gallery
Topic: New OM
Replies: 4
Views: 7086

New OM

Not a new OM guitar, but new flat top Octave Mandolin. This is a completely new model for me, with asymmetric points and 23 inch scale length. In this case I made the body a bit wider and thinner, and sized it to fit into a standard banjo case. I usually avoid points because they are just decoration...
by peter.coombe
Sun Jun 13, 2021 10:39 am
Forum: The Gallery
Topic: Backsides
Replies: 2
Views: 4713

Re: Backsides

No that Qld Walnut stink does not linger in the finished instrument. If I sniff the soundhole I can just detect it, but mostly smell varnish and glue.
by peter.coombe
Wed Jun 09, 2021 2:47 pm
Forum: The Gallery
Topic: Backsides
Replies: 2
Views: 4713

Backsides

Here are a few backsides of some recent mandolins. From left, Queensland Walnut, Blackwood, Red Gum, and Indian Rosewood. I was kind of hoping the Qld Walnut would be disappointing, but quite the contrary. Looks and sounds great, one of the best. It cost me two wrecked bandsaw blades. One when re-sa...
by peter.coombe
Wed May 05, 2021 3:35 pm
Forum: Instrument Builders Forum
Topic: Red gum
Replies: 28
Views: 28634

Re: Red gum

Here are some sound samples - http://petercoombe.com/Pictures/for-sale/Mandolin269/Lord%20Inchiquin.mp3 http://petercoombe.com/Pictures/for-sale/Mandolin269/Hornpipe.mp3 http://petercoombe.com/Pictures/for-sale/Mandolin269/bsa.mp3 This is the first of this style of mandolin where I have managed to g...
by peter.coombe
Wed May 05, 2021 10:06 am
Forum: Instrument Builders Forum
Topic: Voicing a Soundboard
Replies: 3
Views: 3311

Re: Voicing a Soundboard

Chladni testing will give you lots of interesting information, but the difficult part is how to interpret it. How do the patterns correlate to the sound of the completed guitar? If you do get into that stuff I would highly recommend Alan Carruth's video. Otherwise "3", and read the Gore/Gilet books.