| Official Luthiers Forum! http://mowrystrings.luthiersforum.com/forum/ |
|
| Outside mold clamping http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10101&t=51679 |
Page 1 of 1 |
| Author: | bcombs510 [ Sun Mar 03, 2019 9:11 pm ] |
| Post subject: | Outside mold clamping |
Hello, One of the things I like about the LMI outside mold is the attachment point for the two halves of the mold. There is no bulky latch on the end to get in the way of clamping when gluing up the end or tail block. I left it liked this (it’s a Tenor Uke shape).  Anyone come up with some creative clamping that would not be in the way during block glueup? Brad Sent from my iPhone using Tapatalk Pro |
|
| Author: | Clay S. [ Sun Mar 03, 2019 9:38 pm ] |
| Post subject: | Re: Outside mold clamping |
http://www.rockler.com/tite-joint-faste ... 54EALw_wcB These are placed in a routed recess and tightened with a pin. We called them dog bones and used them to join countertop sections together. They also make a simpler version that tightens with a spanner |
|
| Author: | Clay S. [ Sun Mar 03, 2019 9:43 pm ] |
| Post subject: | Re: Outside mold clamping |
These are the other type - in some ways easier to use. www.amazon.com/100pc-Tite-Joint-Bone-Fa ... ooghydr-20 |
|
| Author: | Rod True [ Sun Mar 03, 2019 10:04 pm ] |
| Post subject: | Re: Outside mold clamping |
I always liked Todd Stocks version of the outside body form. Just use a 1/2” bolt with lock but. Self aligns and nothing in the way to prevent clamping of the head and tail blocks. This is my rendition.  Sent from my iPhone using Tapatalk |
|
| Author: | Pat Foster [ Mon Mar 04, 2019 4:00 pm ] |
| Post subject: | Re: Outside mold clamping |
Here's my scheme. It gets dead-on alignment in both axes. I think John Hall might have shown something similar a while back. Attachment: P1060094.jpg
|
|
| Author: | Mike Mahar [ Tue Mar 05, 2019 11:47 am ] |
| Post subject: | Re: Outside mold clamping |
Pat Foster, How do you tighten the nut when the mold is together? I looks like getting a wrench into the space would be really tough. Even a wing nut would be hard to tighten. |
|
| Author: | Joe Beaver [ Tue Mar 05, 2019 2:23 pm ] |
| Post subject: | Re: Outside mold clamping |
I do like the looks of Pat's mold. It is far less cumbersome than my solid, thick molds. I would envision the bolts being tightened with a socket wrench and a long extension. |
|
| Author: | Pat Foster [ Tue Mar 05, 2019 11:12 pm ] |
| Post subject: | Re: Outside mold clamping |
Mike, Joe, They're simple 1/4-20 nuts and bolts, tightened with a socket and box end wrench. |
|
| Author: | Woodie G [ Wed Mar 06, 2019 9:14 am ] |
| Post subject: | Re: Outside mold clamping |
Without remaking your mold, Mr. Clay's suggestion seems the most reasonable, and - unlike the toggle clamps seen on some commercial molds - will not interfere with clamping of the end or neck block when the sides and end blocks are glued up. On the square-cornered molds specifically (StewMac; some of the Waldron molds, etc.)...to my mind, the makers seem to have emphasized low material cost and ease of manufacture over usability in the shop. MDF is close to twice the density of hardwood ply, and less than half the stiffness, so removing some of the excess material seen in the square-cornered design will reduce weight without reducing stiffness where it is needed (LDF is lighter than MDF, but stiffness decreases even more versus hardwood ply). Once your end closures are installed, a few band saw cuts to reshape the mold closer to Mr. True's mold shape will likely mean a 20 percent reduction in weight, which is meaningful for those of us with less in the way of upper body strength that we might wish as a consequence of gender, genetics, injury, or aging. MDF is also quite slippery, so a piece of 80 or 120 grit pressure sensitive adhesive sandpaper applied to one side of the mating surfaces will avoid any alignment shifts in handling (FWIW, a bit of shellac on that mating surface will seal the MDF and make for better adhesion of the PSA backing on the sandpaper). For plywood molds, this is not needed, as the friction of edge-grain ply on edge grain ply held together with a 1/4" bolt or other tension device is enough to keep things aligned without pins or other dedicated alignment mechanism. A modification that goes a long way towards avoiding accidental damage to the rim is the addition of a hanging hole and use of a medium duty ladder hanging hook - available at hardware and big box home stores - which gets things off the floor or table and out of harm's way (see the attached shot). A dedicated hole for a hanging bracket also removes the temptation to use the neck or tail block as the surface in contact with the hanger - an inopportune bump of the head against a rim hung this way can shift the hanger off the block and onto the linings, possibly cracking the side in addition to damaging the linings. Attachment: MoldClosure.jpg Finally, low grade imported hardware store 1/4" steel carriage or hex-head bolt will handle close 3,000 pounds of applied load, so is more than adequate as a closure for molds that will see a few hundred pounds at best of tension on the closures. We ream these holes slightly oversize (0.255") once the molds receive a few coats of shellac and a final coat of Butcher's or Johnson's wax for resistance to glues, etc. A 1/4-20 through hole knob and 1/4" fender washers make for a tool-less mold closure system, although a hex head bolt or wing nut works just as well. Edit: I somehow substituted LMII for StewMac in the original post, but it is StewMac's new molds that suffer from a bit of a weight issue. While LMII's spreader system might benefit from a rethink, and the pinned ends complicate fitting sides and returning the rim to the mold after profiling or a cutaway corner trim block fitting, it is a lighter solution than the smaller Waldron molds or Stewmac products. My apologies to the LMII people for mischaracterizing their product. |
|
| Author: | sdsollod [ Wed Mar 06, 2019 10:12 am ] |
| Post subject: | Re: Outside mold clamping |
I like Woodie's method for hanging up the mold. I may have to do that... I generally make my molds with corners cut off and the ends simply joined with a piece of plywood screwed to the mold with several screws. This way clamps can be used at the neck and tail block as well as all around the sides. Screws are backed out at the end to open the mold. Nothing fancy, but it works... |
|
| Author: | Clay S. [ Wed Mar 06, 2019 11:10 am ] |
| Post subject: | Re: Outside mold clamping |
I make my molds similar to what Rod and Woodie has shown. What I like about that design is that I can add spacers at the ends to increase the width of the mold. I can use a OO-12 fret mold for a OOO-12 fret guitar by doing this, or a size 1 mold for a single O-12 body. Makes for a few less molds to deal with. |
|
| Author: | Bryan Bear [ Wed Mar 06, 2019 11:47 am ] |
| Post subject: | Re: Outside mold clamping |
I do something similar to Clay. I have a mandilinetto/uke mold that uses a spacer between the halves to get the different widths. I have two adjustable guitar molds made form alternating layers of plywood with each layer cut short on one side and long on the other so that they finger joint in together. A bolt or dowel through the finger joints locks them in at the size I am using. Even for a non adjustable mold this would be a good solution. The outline is uniformally bigger than the guitar shape so it is not difficult to clam any part of it and the fastening system does not interfere with clamping or sanding in the dish. My "parlor" mold gives me 12" and 12.75" lower bouts by adding 0.75 inches in the middle at the heel and tail. My other mold is made with a lower bout curve that fairs into itself as I collapse only the tail of the mold. This gives me roughly O, OO, and OOO sizes with the same exact curves but the ratio of the lower bout to upper bout changes since the heel side of the mold pivots instead of getting wider. |
|
| Author: | Pmaj7 [ Thu Mar 07, 2019 1:20 am ] |
| Post subject: | Re: Outside mold clamping |
Carriage bolts. I find the long ones tend to Pivot less.   New username, same Pat Mac |
|
| Author: | bluescreek [ Thu Mar 07, 2019 6:39 am ] |
| Post subject: | Re: Outside mold clamping |
you will soon learn clamping blocks in the mold is not a good thing. You run a high risk of gapping. Start in the mold but take it out use a flexible caul and clamp properly. MDF is also a poor choice for a mold as they are not structural and will move.You can use MDF but put a layer of plywood there for stability. ss for clamping you can run a through bolt in a channel . |
|
| Author: | Woodie G [ Thu Mar 07, 2019 9:22 am ] |
| Post subject: | Re: Outside mold clamping |
bluescreek wrote: you will soon learn clamping blocks in the mold is not a good thing. You run a high risk of gapping. Start in the mold but take it out use a flexible caul and clamp properly. MDF is also a poor choice for a mold as they are not structural and will move.You can use MDF but put a layer of plywood there for stability. ss for clamping you can run a through bolt in a channel . I'll respectfully disagree with the assertion that clamping blocks in the molds - done here for the past 15 years - is not good practice, and offer a technique for accomplishing a gapless, square glueup utilizing the square and true surfaces of the mold and bench. Clamping with sides and blocks level and square against the mold and bench top avoids alignment issues and potential for a twisted rim...particularly with cutaways. Use of two flex cauls above and below the rim avoids Mr. Hall's concerns with gaps and avoids giving away the great advantage of an outside mold - a guarantee of dead square sides blocks, and thus a square rim. The clamping system consists of a single 6" Bessey Tradesman (~$18 online) and four 4" Trademan ($5 at big box stores), two 4" x 1" x 0.100" spruce flex cauls, and the bench as a reference surface. With the mold top side down and uniformly supported by gauge blocks on the bench, the neck and tail block will be square when clamped in place. Once the main 6" clamp is tight and the back side flex caul is on, the rim and mold are placed on edge in the repair vise for the top flex caul and cleanup. We do this with hot hide glue (with some minimal preheat on the blocks), so it does not take long to accomplish. Attachment: RimGlueUp.JPG
|
|
| Author: | Colin North [ Thu Mar 07, 2019 10:55 am ] |
| Post subject: | Re: Outside mold clamping |
It's a bit more work initially, but I dowel and screw extra blocks top and bottom at neck and tail. Lets me clamp the blocks in good and solid, and keeps everything square. I just slipped them back on in the pic, they're only fitted until the blocks are glued.. |
|
| Author: | J De Rocher [ Thu Mar 07, 2019 12:34 pm ] |
| Post subject: | Re: Outside mold clamping |
bluescreek wrote: you will soon learn clamping blocks in the mold is not a good thing. You run a high risk of gapping. Start in the mold but take it out use a flexible caul and clamp properly. MDF is also a poor choice for a mold as they are not structural and will move.You can use MDF but put a layer of plywood there for stability. ss for clamping you can run a through bolt in a channel . My experience with clamping in the mold differs. I've had no problems with gapping. How to best go about clamping blocks to the sides is another example of the fact that there are many ways to successfully skin a cat in guitar building. I agree with using plywood over MDF for the mold. For cutaways, I clamp the side to the head block outside the mold because I just find it easier to set up the clamping. For non-cutaway guitars, I clamp as in the photo. I drop the body mold down so it rests on the benchtop, clamp a caul to the top of the mold, put the block in place with the benchtop and the mold providing the perpendicular alignment and clamp it from above with two cam clamps, and then slide the end of the mold off the end of the bench so I can add two cam clamps from below. I like clamping in the mold because it really constrains movement of the three pieces being glued together and ensures good alignment. Attachment: Clamping tail block to sides.jpg
|
|
| Author: | Bryan Bear [ Thu Mar 07, 2019 3:29 pm ] |
| Post subject: | Re: Outside mold clamping |
I pretty much do what Woodie shows but I'm not confident/good enough to use HHG so I use TB for this. I had problems with gapping until I discovered flexible cauls. I just use a few strips of my solid lining material and that seems to do a great job of conforming to the shape while still distributing clamping force. |
|
| Author: | Pmaj7 [ Thu Mar 07, 2019 8:35 pm ] |
| Post subject: | Re: Outside mold clamping |
I also use clamping cauls that are fitted to the mold for gluing the blocks. They are fitted very tight and the mold and cauls act as one then removed once that job is over. Seems to work very well. New username, same Pat Mac |
|
| Author: | Rod True [ Thu Mar 07, 2019 9:07 pm ] |
| Post subject: | Re: Outside mold clamping |
Im also in the camp of using the body mold as a clamping caul. I use a 1/8” strip if UHMW as a flexible caul for the area above the mold. Never had gaps. One thing I do which no one else has mentioned is I put wax paper between the mold and rim pieces, then place the head/tail block on the wax paper on the bench, thus ensuring I don’t glue the rims to the mold inadvertently. Sent from my iPhone using Tapatalk |
|
| Author: | Clay S. [ Fri Mar 08, 2019 8:03 am ] |
| Post subject: | Re: Outside mold clamping |
I slip a piece of Formica between the mold and sides to keep any glue squeeze out from gluing the sides to the mold. It also gives me something to clamp against. I usually get a pretty tight seam, but if I don't, I don't worry about it too much because the end wedge and the neck heel eliminate any small gap that would show. One way to keep things tight is to loosen the mold very slightly, trim one side while clamped in the mold, then trim the other side using the first to mark the cut lines, then tighten the mold to bring the two sides together. |
|
| Page 1 of 1 | All times are UTC - 5 hours |
| Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/ |
|