Share:
Notifications
Clear all

"Using the Vacuum (Bag)Press"

6 Posts
5 Users
58 Likes
1,053 Views
tv1
 tv1
(@tv101)
Illustrious Member Customer Registered
Luthier
Rep Points: 27896
Joined: 4 years ago
Posts: 3017
Topic starter  

With my Saturday lunchtimes currently unoccupied, I thought I'd use the time wisely.

So I'm just watching the "Using the Vacuum Press" course, with our usual course host joined by special guest @darrenking.

Wow.

Observations;

  • It appears to be quite easy (!) to make laminations out of layers of veneer.  No special tools needed.
  • The Bagpress system seems incredibly easy to use, to shape aforementioned laminations into usefully curved shapes.
  • Looks like an easier approach than using the bending iron.

Now, I'm unsure whether it's Darren's expertise and experience that makes it look easy, or whether it genuinely is as straightforward as it looks.

Question for Darren ...

  1. What's the risk of the sides splitting/cracking as you velcro it into place on the mould?  Compared to the care that Mark needed to take to shape a solid RW side, you seemed to just put the lamination onto the mould and fix it in place.
  2. Does the pressure applied by the press ever cause cracks to appear in the shaped sides?
  3. Is there a limit to the radius of a curve that you can bend a lamination to - eg if someone wanted to make an (eg) cutaway in an LP type shape?
  4. Is there any reason that you couldn't use the same process as the rosette mould to make binding pre-formed to a moulded shape?

 

 

Online guitar making courses – guitarmaking.co.uk


   
Deej, Boo, Robin and 7 people reacted
Quote
darrenking
(@darrenking)
Famed Member
Luthier
Rep Points: 5112
Joined: 5 years ago
Posts: 950
 

Hi TV,

Pleased to hear that you found the lamination videos interesting.

In response to your observations and questions:

Yes, vacuum laminating is very easy and other than the vacuum press kit itself, and possibly a glue spreader, there are no other specialist tools required.

Having used a bending iron simply to bend bindings there is no comparison in the level of skill, and degree of practice required for the two methods - laminating is MUCH easier.

I have never had any veneers split or crack during the lamination process. Typically you would have a mix of 4 or 5 long and cross grain layers of veneer each measuring 0.5-0.6mm thick. Remember that stiffness increases at the cube of the multiple of the increase in thickness and so veneer at 2mm solid is approx 37x stiffer than the same material as a 0.6mm veneer (this is an engineering equation but it is a good enough approximation for Rock 'n' Roll!) This means that tight radii (15-20mm) are relatively easy to achieve. You can go tighter, but the further you push the materials to their limit the more likely you are to see failures. However you, will certainly be able to reliably form much tighter curves using lamination than you would using solid, however experienced you are at it.

Maccaferri guitars have laminated linings which are pressed in exactly the same way as the sides but using a narrow MDF mould which is machined such that the outer surface of the lining matches precisely the internal line of the sides. The difference that solid linings make to the increased rigidity of the body is absolutely unbelievable and this has led me to reducing the number of layers of veneer used in these guitars to just 4, the two outer layers being long grain and the inner layers being cross grain. I have also tried pressing a few sides with a single, thicker cross grain layer of mahogany in the centre as this is closer to the construction used in the originals. This works equally well and results in very lightweight components. Getting back to your question, yes, it is perfectly possible to laminate bindings in just the same way as I have with the linings, I just haven't tried it yet.

BTW, my starting to experiment with laminating guitar parts was due to my bending iron taking weeks to arrive (not from Mark I should add). I think I emailed Mark about something else entirely and mentioned that I was thinking of trying some laminations and he came back saying that the original Maccaferri guitars had been laminated, something I didn't know until then. It was like a significant number of paths in my life all came together at that point. and slotted into place. Spooky!

I hope that I haven't rambled off piste too far but if you have any other questions I am happy to share my thoughts.

Cheers

Darren


   
Deej, Boo, mattbeels and 7 people reacted
ReplyQuote
tv1
 tv1
(@tv101)
Illustrious Member Customer Registered
Luthier
Rep Points: 27896
Joined: 4 years ago
Posts: 3017
Topic starter  

Thanks @darrenking for taking the time for the detailed reply.

Hmmmmmmm ... I’m now thinking about all the fun I could have with new kit in my workshop!

Coincidentally, between my first post and this one, my “neighbour” emailed to say that the other significant piece of incoming kit (think “Aspire” 😉) is probably going to be available sooner than expected.

And with all the time I now have, imagine the possibilities for making all sorts ... 

Online guitar making courses – guitarmaking.co.uk


   
Deej, Boo, Russ and 7 people reacted
ReplyQuote
Jonathan Hodgson
(@jonhodgson)
Noble Member Customer
Luthier
Rep Points: 2035
Joined: 4 years ago
Posts: 330
 

@darrenking

The bagpress system looks great, it gives me all sorts of ideas I'd like to try out in guitar building (says the guy who has still not got started on testing finishes, let alone build 1).

It's probably not the time for me to buy one though (space and justifying the expense). Maybe if I can get a few people at the hackspace interested in building I could organize a group buy of one.

However when window shopping I notice that the link to your online shop is a 502 bad gateway, you might want to fix that


   
Deej, tv1, Boo and 9 people reacted
ReplyQuote
jamesbisset
(@jamesbisset)
Noble Member
Luthier
Rep Points: 1440
Joined: 4 years ago
Posts: 285
 

@darrenking

I have also tried pressing a few sides with a single, thicker cross grain layer of mahogany in the centre as this is closer to the construction used in the originals. This works equally well and results in very lightweight components.

This is so interesting. One of the things currently twinking my twerzle is the required thickness of laminates in guitar construction, as well as the layers. You were intrigued by the 4-5mm thickness (which seems to be common) of the 335 and I wonder whether a semi-hollowbody with internal support at the bridge really needs it? Or does it only need that strength at the mounting points of pickups, switches etc?

Following on from the Maccaferri lamination above, I came across this piece on Yamaha laminated flat tops from the seventies, which suggested the same:

http://yamahavintagefg.com/history-of-the-yamaha-fg-1966-1981-us-models/

It’s widely known that Yamaha made great laminated guitars on the 60’s & 70’s.  Although that is actually not true.  The top, back and sides are 3 ply plywood.  But many people still question that they aren’t actually solid wood, because they don’t sound like plywood guitars, especially the earliest models.  Plywood is a wooden board consisting of 2 or more layers glued and pressed together with the direction of the grain alternating, typically 90 degrees.  Laminate is a wooden board (in the case of guitars) consisting of 2 or more layers glued and pressed together with the direction of the grain in the same direction

The plywood of vintage Yamaha guitars were made differently than today’s plywood.  All the layers of the top are tone wood, not a cheap wood filler.  The top has 3 layers, thin top and bottom plies and a thick mid ply (oriented perpendicular to the top and bottom plies), making it hard to tell that it isn’t solid wood.  If you take a close look the sound hole with a jeweler’s loupe or magnifying glass you will see it.  The back and sides are also 3 plies, with the inner ply being a different wood (filler).  But the outer plies are both tone wood.  You can tell the sides and back aren’t solid by looking at a grain pattern or a defect on the outside and looking for the same on the inside.  The inside will be different, even though it looks like solid wood.  It really is, but they were made with saw cut plies, and not today’s rotary peeled log plies.  The grain of cut vs. peeled wood looks very different.  Almost all commercially produced vintage Yamaha FG’s for export are plywood.  This is because of the uncontrolled climate (temperature and humidity) on the ships carrying them to America.  Many earlier solid wood Yamaha guitars cracked in shipping.  Plywood pretty much guarantee that won’t happen.  Also, the 100 series guitars were very lightly braced.  The combination of all tone wood plies and very light bracing gives them the sonic appearance of a solid wood guitar.

I take all of this with a pinch of salt (when is plywood not plywood), but as a semi-hollowbody is trying to achieve some sort of acoustic response, trying to assess the impact of weight, stiffness and resonance on the tone and dynamics will be a significant part of the design process.

Jack of all trades and master of my own destiny. It’s only a small destiny.


   
Deej, mattbeels, Russ and 7 people reacted
ReplyQuote
Boo
 Boo
(@boo)
Illustrious Member
Luthier
Rep Points: 34813
Joined: 5 years ago
Posts: 3830
 

@tv101 and @darrenking I have to admit that this Bagpress stuff has completely passed me by, I’m ashamed to admit. I can understand the principle of it but have not looked at it in detail, so I think I should. 

It would be good to see what you come up with TV, I bet you’ve got some good ideas already. 👍

After I’ve wrestled with this buffer for a while, I’ll watch the videos that Darren kindly made. 

Man I love this forum. 

Make guitars, not war 🌍✌️🎸


   
Deej, mattbeels, Russ and 3 people reacted
ReplyQuote
Share: