shop tips

Sandblasting System Back End

Back by popular demand – sandblasting!  I am delighted to profile my complete sandblasting system.

The starting point is my “nothing special” $75 Craiglist compressor in the basement of the barn, residing there because it is a diaphragm compressor head rather than a piston head and thus pretty noisy.  The compressor unit is a 2 HP motor/head attached to a 10 gallon tank.  The compressor is attached to the air-abrasive gun via a typical reguator/air hose system and quick-release pneumatic fittings.  I generally operate my blasting gun at around 40 psi which gives me good control and adequate aggressiveness and is well within the capacity of the compressor.

The blasting gun attached to the hose is a siphon-feed unit, ancient (probably Craftsman) but indistinguishable from some thing you could buy tomorrow at Harbor Freight.

 

The system operates like this:  The air running through the gun nozzle creates a partial vacuum in another feed-line fitting/tube which draws the abrasive medium through the siphon tube.  In that effect it is identical to a paint spray gun, but instead of pulling up liquid paint and atomizing it through an atomizing nozzle it is sucking up the abrasive and focusing it through the gun output aperture.  As a general practice I simply jam the end of the siphon tube into the bottom of the abrasive reservoir, almost always just a bag of the abrasive or a five gallon bucket if I am feeling fancy.  I refill the bag/bucket with “overspray” abrasive gathered from the trash can.  I’ve thought about getting a fixed metal “hopper” reservoir but the bag/bucket work just fine for me.

One final word: make sure to wear eye, hand, and face protection.  Really.  I generally use a face shield, light leather or rubber gloves, and a dust mask or respirator.  You do not want to get even a smidge of this in your eyes or lungs.

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BTW I got my stitches out yesterday and much to the doc’s surprise I have had zero discomfort since Saturday, when I became pain free and cane free.  As he commented, “This level of recovery is unusual for someone at your stage of life.”  Apparently for geezoids like me the cartilage pain is compounded by an even more severe arthritis pain, which I do have some but not yet to the serious pain level.  If arthritis is the foundational pain problem, repairing the cartilage will not diminish the pain to my current level of “0.”  Still a little stiffness but that will disappear with motion and PT.  I’ve been told to take it easy for a month, which I will probably sorta do.  Off to mow the lawn.

Winnowing and Strategerizing (sorta “Workbench Wednesday-ish”)

The events of the past several months, including Mrs. Barn and me losing our remaining parents and my becoming closer to 70 than 60, are leading me on a path of deliberate winnowing of my shop and barn contents.  Given that my sister is still going through my mom’s stuff — and she lived her last years in a one room “mother in law” apartment with my brother and sister-in-law — and the literal tons of belongings in my father-in-law’s four bedroom, two car garage house with a large back yard where he lived for 59 years, I am determined to reduce my material possession burden to my heirs as much as possible.  Since my mom died at 103 I may have some time to get it all resolved, which is a good thing when there are 7,000 square feet and 70+ acres in the discussion.

Other contributors to this long-term process are the realizations that barn-based workshops will not have the prominence that I once thought would be true, and given my current set-up on the fourth floor I really do not need a second floor classroom outfitted with a perimeter of workbenches (I do however still use that space mostly for development of the ripple molding cutter).  Also I recognize that at some point in time life in the mountains would just become too hard physically, and I would see the barn in my rearview mirror.  Not any time soon, but it is inevitable in 10, or 15, or 20 years.  One small step we are taking to delay that day as long as possible is to try to find someone who can execute most of the mowing and bush-hogging tasks around the homestead, but when you live in the least populous county east of the Mississippi River it can be a challenge to find someone to work for you.

One of my upcoming tasks will be winnowing the workbench inventory.  Do I really need eight workbenches in my own workspace?  Of course not.  So, I will begin reducing that particular footprint almost immediately and there are definite “Workbench Wednesday” implications.

The first of these will be to replace my first workbench built for the space, the timber planing beam, with a low bench of the Jonathan Fischer/Roman/Estonian variety.  Since completing my French Oak Roubo Project bench I have had no need for the planing beam so it will be resawn and joined to become the slab for that bench.  It will occupy roughly the same space but serve a more immediate need as my knees and hips are becoming more troublesome and working while sitting is ever more congenial.

This change will also allow me to construct a standing tool chest to hold a copious inventory of hand tools, to be placed at the end of the low bench where my saw rack and metal hand planes hang on the wall.  Since seeing Walter Wittmann’s cabinet a few years ago I have seen this as a solution to my tool storage problem and now is the time to act on it.  The Japanese tool box will reside where Walter’s large lower drawers are located.

Of the plans for the workshop changes these are two of the three at the top of the list.  The third is to restore my piano-maker’s workbench in order to make it a proper gift for my son-in-law, and move it out of my workspace.  I m still cogitating on the ultimate home for the Studley-ish bench I built for the exhibit.

On top of everything else I have stock for at least another half dozen workbenches still unbuilt, but that may be moved on to other folks with the time, energy, and need that I do not have.  Among these are the gigantic mahogany slab and vintage walnut 6×6 that would result in an eye-popping Roubo bench, a 14/4 curly maple slab already glued up, a stack of oak 10x15s, some 12-foot long 7×15 Douglas Fir timbers…

Stay tuned.

Restocking

Decades ago I discovered the benefits of keeping a stash of emory boards at-hand in the shop.  Bought at the local pharmacy I found these little tools to be a magnificent solution to any number ot abrading and shaping problems.  Unfortunately, like a great many products over the years these have become too cheezy to really be the workhorses they used to be.

So, as I have posted previously, I make my own.  One of my beginning-of-year habits is to make a new set of abrasive sticks, gluing sheets of sandpaper to tongue depressors with a spray adhesive and then cutting them apart into a pile of useful tools.  (I really don’t need any posts about my New Year’s regimen of sharpening routine edge tools, do I?)

This year I did something a little different and expanded the variety of sticks.  In addition to the typical pairing I’ve been using for a long time, a coarse side and a medium side of aluminum oxide abrasive, I added finer stearated silicon carbide papers into the mix.  These options created their own issues, as I found the adhesion to be not as robust as with the AlOx paper.  Using a small roller, made by and given to me many years ago by my pal MikeM, I found that pressing the edges worked well, plus I discovered the need to embed the sticks while the spray adhesive was still soaking wet.

I wound up making three different sets of abrasive sticks.  The specs for each was detrmined by the abrasive sheets I had on the shelf.

The first set was pretty similar to ones I’ve made  the past, this time with 60-grit and 100-grit sandpaper.  I think that the 60-grit side will be less useful than I originally thought, but that could be because the product itself is pretty cheap and the abrasive particles spall off with first contact to the substrate.  Next time I will aim for 80 and 120-grits.

Next up are the sticks using SiC papers, 150-grit and 220-grit papers.  I’ve not made this combination before and think it will be a very satisfactory one.

Finally I went utra fine, with 400-grit and 600-grit together.  We’ll see how useful these are in the coming days.

I’m now set up with this year’s inventory of abrasive sticks.  Well, we’ll see if this lasts my usual full year since there are now so many different options.

 

 

Salvaging A Busted Sharpening Stone

Among my inventory of sharpening implements is an old 8000-grit ceramic water stone that I bought perhaps 35 years ago.  I recently dropped it on a concrete floor with the resulting carnage you might have predicted — it snapped in two.  Rather than toss it out I tried to salvage it and put it back to work.

Based on the character of ceramic sharpening stones, namely that by nature they are comparatively porous, the foundation existed for adhering the two pieces back together.  In fact, since ceramic stones tend to be fairly soft and friable (fracturable) when adhering pieces of these ceramics together you have to pay attention to the adhesive-adherend margin, making sure that the density and hardness of the adhesive is congenial to the density of the adherend.  While I cannot modify the character of the cured adhesive film, I can use other methods to modify its performance.

In this case I followed my longstanding practice of using dilute adhesive to size the gluing margin (the surface of the adherend), thus rendering something more hardened-sponge-like than a block of hard plastic in direct contact with the soft ceramic.  The latter construct is much more likely to fail in somewhat short order as the harder, denser, and more cohesive adhesive breaks off some of the softer ceramic block, resulting in the failure.   In this case I used an epoxy I had on hand.

I mixed the two parts thoroughly, then diluted it immediately with with acetone to yield a watery solution.  This was applied directly to the broken stone surface, and soaked in to yield a fairly parched-looking surface.  This results in an adhesive/adherent region perhaps ten or twenty of fifty times wider than that accomplished by full-strength epoxy alone.  After a few minutes I added another application of the dilute epoxy, then set it aside until the epoxy was almost tack-free.

The it was ready for a bead of the full strength epoxy, which I applied to the lower half of the joint to make sure none of the full-strength epoxy would squeeze out the top glue line to excess.

Once the gluing surfaces were coated with the epoxy I placed the two halves together and applied very gentle clamping pressure, mostly to hold the two halves in correct alignment rather than drawing them together.  Their fit was wonderfully tight from the git-go.  There was a tiny bit of epoxy squeeze out on the top line, and I wiped that off immediately with a paper towel sodden with acetone.

I let the assembly sit until the epoxy was fully hardened, then re-trued the surface, first with a sheetrock screen and then with sandpaper over a flat surface.  Since it is an ultra-fine polishing stone it does not need much water; to make sure the epoxy is not challenged I simply wet it on the surface instead of soaking the stone in the water bath.

In use there is a little click as the steel is passed over the fracture line, but the stone still works just fine.

Old School Pumice “Sanding” Block

A few days ago blog reader (and the Lou Gehrig of the woodworking blogosphere) RalphB asked about my use of the pumice block to smooth the surface of my parquetry Kindle case.  The use of pumice blocks is well documented in historical accounts, although explicit or specific details are often missing.

I use a pumice block from the plumbing section of the hardware store (I order them by the case).  Normally they are used for deep cleaning of porcelain and enameled fixtures to remove mineral deposits and stains.  They work equally well for evening out irregular wood surfaces such as those found when assembling parquetry or marquetry from sawn veneers, where regardless of the care in the initial veneer sawing a fair bit of irregularity is manifest.

I generally use a pumice block as the step following the toothing plane/Shinto rasp, moving the block in a circular fashion on the substrate, yielding a fairly smooth and even surface about what you might expect with 60 or 80 grit sandpaper.  Following the pumice block with a card scraper and polissoir, the result is quite pleasing.

Fumes

In my ongoing efforts to replicate Asian lacquerwork without the use of urushiol, the resinous sap from the poison sumac tree that is refined into the coating material, I have been trying a number of alternate options including epoxy, oil/resin varnish, shellac (of course!) and varieties of polyester coatings.  The air flow through my studio is controllable and just about perfect for any non-spray finishing from a clean environment perspective.  However, virtually all of the polyester products produce noxious fumes when the coating is reacting.  Not enough to be hazardous to my health, but plenty stinky enough.

To deal with the problem I have dusted off my old favorite respirator, the 3M EZ Air that fit my head and face perfectly and is comfortable enough that I can wear it for hours.  Naturally since it was such a satisfactory product it is no longer available on the market.  The organic vapor cannisters are available so this will remain my “go to tool” for respiratory comfort when working on the polyesters,

Though a satisfactory solution for ambient odors I also came up with another one for scrubbing the air inside a curing chamber.  When I can, I place the newly coated object in a box along with an air scrubber I made just for those occasions.  The unit starts as the jar containing activated charcoal flakes, normally used for aquarium filters.

I cut a hole in the lid and affixed a compewder fan and a screen, and drilled a series of small holes in the bottom of the PET jar.

I sifted the activated charcoal to remove any powdered charcoal dust, something I do not want blowing around inside the drying chamber with a wet coating in the immediate vicinity.

I placed the clean activated charcoal flakes back in the jar and closed up the whole system.  Now I can coat the object the the polyester, flip a large cardboard box over onto it to enclose it, and turn on the scrubber.  By sucking in the air gently and blowing it through the container of the activated charcoal (which adsorbs the organic molecules off-gassing from the polyester) it removes the odors and I cannot really even notice them while I am at work nearby.  When the coating is cured I remove the object and the smell is negligible.  I find that if I leave it all in over night there is barely any odor at all.

When the air scrubber or respirator are not in use I leave them in sealed containers to extend the working life of their filtering components, whether activated charcoal flakes or organic vapor scrubber cartridges.  The fan scrubber goes into a gallon-sixed freezer bag and the respirator into a little sealed box.

Exploiting Kinesiology (a/k/a The Seven Minute Camber)

When it comes to sharpening plane irons I am a sidewinder.  I taught myself how to sharpen and this was the way that made the most sense to me as it exploits the natural kinesiology (the study of human motion) of the hand and arm.  Straight-ahead sharpening fights the natural motions of the body as you have to constantly adjust the angles of the shoulder, elbow, wrist, and hand.  Sidewinding takes advantage of the swinging motion of the arm.  All you have to do is establish the bevel angle of the iron and everything else takes care of itself with minimal attention.

The pendulum motion of the swinging arm makes it almost effortless to shape a camber on a plane iron.  This one was a new one for a Bailey #5.

My initial shaping of the bevel contour is done with a 60-grit belt on my 50-cent granite backsplash block.  My first step is to gauge the bevel angle, which I determine by setting the iron  bevel-down on the abrasive surface until the tip and the heel of the bevel are both in contact with it.

Then I start to introduce the curve on the bevel tip by rocking my body forward and backward, and swinging my arm in a pendulum fashion, moving the iron back and forth on the abrasive belt while maintaining the bevel angle.  As I am doing this I rotate my hand to push down with my thumb and grind away the trailing corner on the push stroke and press down with my index finger on the opposite corner on the return trip.  It really is almost effortless and idiot-proof.  For this part of the process I usually wear cloth work gloves as the iron gets really hot, really fast.

After I get the curved tip I want I move on to finish the iron on my 220 and 1200 diamond plates, then finish it off with the 8000 ceramic stone.  Sorry for the fuzzy pic, it’s the curse of the “Automatic” setting on the camera.  I use the exact same motion for the sharpening stones as I used for the rough shaping on the granite block.

Originally I titled this post “The 5-Minute Camber” but I timed myself as I created this one.  I was off by 40%.  It took me just over seven minutes to go from start to finish.  Shoot, I took longer to do the photography.  I’m trying to teach myself to make short “shop tip” videos, maybe this process would be a good candidate.

Happy Accidents – Counterrotation Edition

This summer has seen a frenzied pace on the homestead, with summer lawn and garden activities, family comings and goings, working on the book manuscript and photography, and now, the final sessions for recording the Gragg Chair video.  Chris my videographer has been even more occupied than I given that last year he started a new, full-time job, he and his bride bought a new (to them) house with all the attendant time sunk into that as required, and just recently a brand new baby.  All that to say it has been almost a year since we were able to get an intersection between our two calendars, and that intersection occurs tomorrow.

Combining my preparations for that with my ongoing Gragg Chair Challenge I’ve been spending a lot of time up in the attic studio workshop, just as we have been experiencing our summer heat wave with many consecutive days up in the mid 80s.  The locals are griping about the heat whenever they get together to chat about anything.  One implication of the warm sunny weather is that the attic workshop is crowned by almost 3000 square feet of uninsulated roof, the material of which is heavy corrugated asphalt panels.  So, if the sun is shining the overhead ceiling becomes a high temperature radiating panel.  My thermometer indicates that the static room temperature is often well over 100 degrees.

To mitigate this effect and make the space useable I have a three-foot low speed exhaust fan.  When it is running and sucking cooler air from lower volumes of the barn, the space is a congenial working environment.  Then, last week the motor burned out for the fan.  Since that motor was one of a group of motors I rescued from a dumpster 25 years ago I was not overly distraught that I only got a dozen years of service from it.  I immediately grabbed another, identical motor off the shelf and installed it.   Only when I threw the switch did I discover that I had failed to confirm the motor’s rotation before the installation, and the fan was blowing outside in rather than sucking inside air out, the way an exhaust fan is supposed to be set up.

The happy ending to the story is that the fan running “backwards” renders the space even more comfortable than running properly!  The robust flow of cooler, outside air flowing over me while working makes my time there even more joyful than I was expecting.  I just might leave it that way.

 

Between A Rock And A Hard Place

Well, maybe a concrete block rather than an actual rock.

While recently at our daughter’s house I had a trimwork task that required a nice wide, razor-sharp chisel.  Unfortunately the only  wide chisel I had was this Stanley one I bought from Big Blue for some demo work, and the dentated beveled edge confirms that usage.  (This picture was after a minute of working on it, so it was a lot worse when I started out)  Were I back in the mountains I would have had no trouble rehabilitating the edge but at that house I only had a fairly fine sharpening stone.  So, I remembered a legend from my early days in the trade, when Pop Schindler had to re-cut some joinery while on-site for a project and simply picked a screwdriver from the installation tool kit and sharpened it on the curb to make it into a chisel.

I had the advantage of starting with a chisel, albeit a really beat-up one.  Instead of the curb I  carried a concrete block into the basement workshop and started working on the edge.

This picture was after about three minutes; after another three or four minutes with the concrete block I had re-established the bevel edge.  I did take another few seconds to flatten the back.  Like I said, it was a demolition chisel before this.

Another minute or two on the water stones and I was up the stairs to trim the door.  The chisel notched the vintage cherry trim like it was a hot knife going through butter.  My only hurdle was the contortions required to get the tool in the right place to work.

Testing The Envelope

There are times when I am working on the book manuscript when I just have to get up and do something physical for a change of pace.  Because of the peculiar way I write, editing and massaging-together is often more fatiguing than the original creation of the first draft so I need a diversion and relaxation.

Last week I spent an hour or so at the lathe trying to see how thin I could turn a bowl.  This concept interests me as I begin my re-immersion in replicating Japanese lacquerwork, a creative theme that will be prominent in the studio and on the blog for the foreseeable future.

I had a block of c.1840 11/4 old growth cypress handy and gave that a try.  I do not know why I had never turned the cypress before, it works like butter in the lathe.  I left the face of the block square as I am trying to come up with a form that suits my fancy, and a square/turned bowl with a feather-thin edge is intriguing.

I found out that feathering the edge is not possible without reinforcing it somehow, probably by impregnating it with epoxy, or the edge will simply shatter as you work it.  Ditto the base of the bowl where I did indeed find the edge of the envelope.  I tried the a similar exercise with some figured plum stump I harvested 15 years ago.  Same result.

Since failure is its own useful data point I now know I need to turn this form close to finished, then impregnate and finish up then.  I will report back on those results.

The next day I  tried the exercise with a southern yellow pine scrap and also had encouraging results.

One of the peculiar and captivating phenomena of that attempt was the turning began to “sing” as the wall was thinned, sounding much like a crystal goblet when it is being played like a musical instrument.

Then, back to the Eames chair knockoff for more wordsmithing.