Contributor
Looks to me like it would work Jim...at least as far as configuration. Not sure how the moisture content will affect adhesion. I've had pieces in the past that I had to heat up with a propane torch to get some dryness and that worked ok. Other times....well....not so much
Fun times
~john
"There's nothing wrong with Quiet" ` Jeremiah Johnson
Contributor
I'm a "funky wood" guy and I do a lot of void filling with epoxy, but in almost all cases I rough turn green, dry the piece, then do the required epoxy fills and finish turn. If there are cracks or defects I'm worried about staying in place during initial turning, I usually use cyanoacrylate to reinforce things enough to do the roughout. Turning any piece of wood is potentially dangerous, though certainly some more so than others. Best to assume that any piece of wood could fly apart at any time.
I agree that the nature of the void is such that I wouldn't be overly concerned about the stability of the fill, if it were dry. Not saying it wouldn't work green, just don't have much for experience with how well epoxy bonds to green(ish) wood.
Some thoughts if you decide to plunge ahead:
When doing the fill, I would begin by soaking the area well with straight epoxy with no additives (fillers). The goal here is to get the good penetration of the degraded areas. If you just begin with epoxy with filler, the fill can end up kind of "starved" for epoxy if a lot of the epoxy soaks into the wood and leaves the fill area too dry.
Epoxy resin changes in viscosity a fair amount with temperature. You'll get better penetration if the resin is warm (say 80 F). It will also set faster at this temp -- choose your hardener accordingly (see more on this below). Warm epoxy will also purge bubbles better (lower viscosity).
Fresh epoxy bonds completely with uncured (still soft) previous coats, so this initial soaking is a first step in a "fill session". When the wood seems to have been saturated with straight epoxy, but before that initial epoxy is set, add the main fill. Assuming that your fill will be opaque and not clear, you're not going to see much of that funky texture that's showing now (which I think is kind of cool). If you just use only tinted epoxy (no filler), my own sensibilities are that it's going to look kind of "plastic" and not in keeping with the "organic" features of the wood. For this reason I would use a semi-chunky fill, so that the fill has some visual texture. Were it me dealing with this piece, I would use a combination of ground coffee and crumbles of bark (say 1/8" to 1/4" max). Epoxy soaks into both pretty well and they end up giving the fill a pretty uniform hardness, which helps with both final turning and sanding.
The ground coffee will give the fill a dark brown color. In most cases, I find I get a better look from filling far darker than the surrounding wood than trying to match it. However, you can use a lighter color filler (e.g., wood flour) and tint it with Transtint dye or pigments (just Google epoxy pigment) if you have a particular color in mind. A lot of people say they just add enamel paint, though I've not done that myself. If you want to go psychadelic, get some mica powder (gives a pearlescent look). I tend mostly toward a more natural look, and am usually trying to keep the fill in the background visually, rather than accentuate it. It's funny that dark brown fills generally don't draw that much attention, even if it contrasts pretty strongly with the surrounding wood. But some folks do flashy things with fills.
This is not a job for 5-minute epoxy, you want a slower cure so there's time for it to soak into the wood, and for bubbles to rise out of the fill. I would use a slow hardener for the initial coating of the wood -- you want this to set up slowly so there's maximum time for penetration. You could use a medium or fast (but fast is not the same as 5-minute epoxy) hardener for the main fill.
I get my epoxy from raka.com (no affiliation, just a satisfied customer). They offer kits (resin + hardener) in different volumes at what I've found is a very good price. One of the really nice things is they will do is to sell you kits that include more than one hardener and still give you the kit price. For example, if you order a 3 quart kit (2 quarts resin and one quart hardener), you can get it with 2 quarts resin, one pint fast hardener, and one pint of slow hardener at the same price. Their website isn't very sophisticated -- if you want to do a special order like I just described, call them to order.
I find it much easier, and much more accurate, to mix by weight rather than volume. For $5 or $10 you can buy a cheap digital scale that will measure to the tenth of a gram. The raka 2:1 (volume) resins mix in a 100:43 ratio by mass. Yeah, that sounds complicated, but there's a calculator on your phone if you can't do it in your head. Multiply the grams of resin by 0.43 to get the hardener mass. 10 g resin, 4.3 g hardener. Buy some small (like 2 oz) disposable plastic cups to mix in.
Epoxy produces something called an "amine blush" when it cures, which is kind of a greasy surface layer. If you let one application of epoxy cure before you add the next, this amine blush will interfere with the adhesion of the second layer to the first. That's why I suggested doing multiple fill steps all in one overall session. If you do have to pause, you need to wash the amine blush off, or sand the previous layer well in order to get good adhesion. Since you're relying on this fill to stay together while you're spinning it fast, you want to make sure there is good adhesion. Best is to do it all one overall session where each addition is going over an previous layer that is not fully cured.
It's hard to fill big voids on the outside of round things so that the fill is complete -- you have to build a pretty good size dam. For that reason, it's often better to fill them before you're too close to final dimension, so that if the fill is a little shy it will still turn down to round.
Have fun!
Dave
Last edited by Dave Mount; 09-04-2019 at 2:41 PM.
Member
Hi Jim, I'm a novice turner and by no means any expert on this, but I've been experimenting a little myself filling voids. with Alumilite Clear cast I bought from Hobby Lobby. I added Alumilite mica powders for color, with overall good success. I have used vinyl tape for the dam and sometimes had to pour more than once. It isn't expensive and does add stability and color to the bowl or vessel. My biggest problem so far has been trapped air bubbles. I do like the idea of bending light sheet metal to make a form. Good luck!
Contributor
I agree with Dave’s post on using epoxy. I got years of experience with West System epoxies through an ill-advised acquisition of an older wooden boat..still use epoxies even though the boat is long gone. Amine blush is usually easily washed away with a little soap and water.
The option is to add a patch to reduce or eliminate the epoxy fill.
I had a piece of Black Acacia the was destined for a large fruit bowl - 18” diameter. Originally planned to fill the bark inclusion with epoxy, but decided that, since it didn’t need to hold soup and it was holding together through the roughing process just fine, to throw is a few dutchmen/butterflies to hold it all together.
Decided it was a good opportunity to do through butterflies - mortise deep enough to show through both inside and out. A few in process photos - no finish yet...CBE5BBD6-C21C-4859-BC05-15C208CAEE5A.jpg625150A5-E980-4CF6-B288-2465AEF106CB.jpg61FDFE22-A272-4470-94B7-BE9240063C11.jpg
Member
Roger that John Hart...We are told by the media that everything will hurt you or kill you. Every hobby I ever enjoyed, and every job was dangerous. Including Offshore oil, Forestry, offshore fishing, sailing skiing ect. Did we get banged up--for sure--so what. The same in turning for 30 years but we were not made to be safe and comftorable and bored. Life is too short to sit on he bench and not try the unknown and untried. I have discovered more unique procedures and tools than I ever read about and never had a lesson. Learning something yourself is far more pleasurable than being trained. Sure we learn from others and should share our tricks but we should not be discouraged. It's supposed to be fun. The Forum is lacking in spontanity and enthusius as is our local turning club.. Far too many clicqes and push back,s in the crowd me thinks. Too many regulations and rules in this world now. If you read any history or economics this is readily proven. Have fun and experiment your heart out.
Contributor
Cool Bowties Jeffery!!
~john
"There's nothing wrong with Quiet" ` Jeremiah Johnson
Contributor
Agree, love the dutchmen. Can you outline your process for cutting the mortises?
Dave
Contributor
I use a standard inlay kit (bushing and matching bearing and a spiral bit - I think mine is from CMT but there are several on the market) with a template hot glued to the blank. I generally cut my own templates from expanded pvc board like Sintra (ask for scraps at a sign shop). You can easily cut 3mil or larger with a utility knife. 3mil seems to be stiff enough and holds up to the hot glue well.Originally Posted by Dave Mount
The 1/8” spiral bit needs to be able to cut to a minimum of 5/8” deep plus the thickness of the template - need to look around for extended bits.
Chuck up the bit in a trim router, put on a respirator and make small cuts until you’re about 5/8” deep. 1/8th inch bits don’t have a lot of cross section for heavy cuts at depth. Go slow. Finish corners with a chisel or knife.
Same template makes the dutchmen on whatever stock you like.
A couple of thoughts that came up as I wrote:
Seems like a 1/4” bit would go faster, but then these are the largest I’ve done so far - most are smaller - and I don’t think I’ve seen an inlay set for a larger bit. Now the google machine needs to be fired up...
Play with the template - I mark up the blank with a pencil til I’m happy with the layout.
Be aware that going all the through to break the inside surface means that the dutchman is probably significantly weaker than one that only goes partially through the bowl wall. There’s less glue surface and a higher proportion of end grain. I didn’t think it was an issue for a fruit/display bowl.
Member
Jeff, would both the dutchman and epoxy work, completely filling in the void?
Moderator
From the picture it looks like some of what's left may not be very strong. Could it come apart, epoxy or not, as the inside is removed?
A friend of mine turns things which stayed together when the outside is shaped would easily disintegrate when hollowed. He solves this by turning the outside first then wrapping it with reinforced strapping tape.
JKJ
Member
I use lots of epoxy. I buy regular "bar top" epoxy by the gallon it's a 1:1 resin catylist mix. Like Dave, I'm a 'funky wood" guy, turning blanks green and filling the voids after they dry for final turning. Sometimes turning a funky piece while green can be dangerous. You can't see if that fissure goes all the way thru and may let go sending schrapnel straight in your face. Face protection is a must. There are also goo, sap, beetle larvae, and carpenter ants in the mix. Cyanoacrylate will help sometimes and it may be helpful to brush on an epoxy/acetone mixture. Acetone is a solvent for epoxy and will not inhibit the cure, but makes epoxy penetrate funky wood. For large voids, dams of masking tape, and pieces of milk jug plastic taped on will help. Adding sawdust or coffee grounds to the epoxy will inhibit the tendency of epoxy to drip and when cured, has the apperance of a bark inclusion. What customers really like is the addition of colored stone to the mix. I get mine pre-ground from https://www.etsy.com/shop/Thegrindingshed. (not affiliated) Great people with LOTS of different colors and particle sized of gemstone and other minerals. My favorite is chrysocolla. Some of the minerals are quite high on the MOHS (hardness) scale and will dull an M42 gouge immediately, so carbide is necessary when finishing stone inlays. Abrasives are a must for final finishing. With bar top epoxy after an overnite cure you can proceed to final finishing, but often more than one pour is required. Always do an experimental cure before you mess up a piece of wood. Sometimes the temperature and mixing errors will keep the mix from hardening, so be sure of your mixing method, whether by weight or volume, and adhere strictly to your chosen mixing protocol. Epoxy seems to have a long shelf life. I have had epoxy for 10 years which seemed to be OK.inlay gp.jpg
Last edited by richard shelby; 09-05-2019 at 11:00 AM.
[OP]
Contributor
Thanks to all for the comments, advice and concerns. The detailed explanation on the use of epoxy by Dave Mount will be of help for many projects to come.
If this piece holds together and I am able to finish it I will post a picture or two. Thanks again.
Member
I use the aluminum tape on my bowls all the time. Agree,it sticks great and you can form dams etc. I suggest using some hot melt glue around the edges to prevent the epoxy from seeping under the tape. I sometimes reinforce it with painter's tape just to be sure.
Moderator
I'm certain the community would like to hear about your experiences, good or bad!
JKJ
Contributor
Sure - You’d still have the problem of creating a dam. I use hot glue to build up a fence around the void.
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