Thursday, May 31, 2012

Chip off the Old Block

I think the sub-blade of the Japanese plane, termed uraba (裏刃) or osae-gane (押さえ金), is worth a thorough look. Some writers, such as Odate Toshio, have mentioned the idea that the chipbreaker allows less-experienced and less-skilled workers to plane wood without tear out. I can see this being true in some cases however there is a lot involved in getting the chipbreaker to perform properly, and a lot of that savviness is not going to be obvious at all to the inexperienced. I don't believe I've cracked all its secrets yet, and continue my efforts to gain understanding in that regard.

The sub-blade is illustrated in white in the drawing:


I'll throw out a few Japanese plane terms here and there as I go in this series of posts, and you'll see I have referenced all of the terms to be used on the above drawing. Of the two Japanese terms for chipbreaker, uraba (back blade) and osae-gane (pressing-metal), I prefer the latter term osae-gane, and intend to use that term, or or 'sub-blade', fairly frequently in this series of posts. Either is, after all, shorter to write than 'chipbreaker'. And by the way, the term '~gane' is pronounced 'gah-neh', not like 'gain'.

The sub-blade does not cut anything - the main blade does all the cutting. The osae-gane does manipulate the shaving produced by the cutting action of the main blade. And it does a few other minor things besides:

  • pre-tensions the main blade's cutting edge so that it deflects less under loading
  • adds a slight heat sink effect which prolongs the edge retention of the main blade
  • helps compensate for a loose fitting blade at certain times of the year

The heat sink effect is rather minor, so I tend to think it is best ignored. The mass is in the main blade, so most of the heat sink potential is in the main blade. The sub-blade is fitted onto the main blade under tension, the load imposed on top of the osae-gane by the metal pin known as the osae-bo, (lit.: 'pressing stick'). As far as the fit-compensating effect of the osae-gane on top of the main blade, that effect should not be too large so long as the main blade is properly fitted. If the main blade is properly fitted, the dai should be fully supporting the blade nice and low down in the pocket. Having a crappy fit there and expecting the sub-blade to make everything all right is not going to be a recipe for success in most cases.

The pre-tensioning effect is this: the main blade's bevel, as one moves out to the cutting edge, becomes progressively less supported and therefore more prone to deflection under load. A certain amount of that deflection associates to the inherent elasticity of the laminated blade and also to the angle of bevel on the main blade. The osae-gane pushes down onto the very end of the main blade and some of that elasticity is taken up. This pre-tensioning effect should therefore lead to a reduction in any propensity of the blade to chatter while cutting.

If the fit of the blade is not the best, or becomes sloppier at a certain time of the year, then the sub-blade can help to take out some of the sloppiness however the pre-tensioning potential will be reduced. One can bend the ears of the sub-blade a bit more so as to increase the pressure on the edge of the main blade, or shim under the main blade with paper, however a better solution, ultimately, is to have a separate plane block for use at those times of the year when the fit of the main blade is unacceptably loose. Winter planes and summer planes. If you live somewhere without substantial swings in humidity, then you will probably be able to get by with the same plane year round, so long as the fitting of the main blade is done properly from the get-go.

The sub-blade should not be considered a means of compensating for a poorly fitted main blade! If the fit of the main blade is irretrievably poor, cut another dai.

Let's assume that the back of the main blade has been properly prepared and there is a sufficient landing at the cutting edge for the sub-blade to press against. Let's assume the sub-blade sits on the main blade without clattering, and that the fit of the sub blade edge is perfectly tight against the main blade. What does the sub blade really do - and does it offer any advantages in comparison to a single blade plane? Is it, as Odate suggested, a means by which less-skilled carpenters during wartime could accomplish good planing results, or more than that?

In this series I am going to look closely at the true functioning of the sub-blade, at least as far as I understand it, and will argue that it does more than overcome inept carpentry technique. The sub-blade, as we shall see, allows a plane with a lower blade bevel angle to successfully work difficult materials - to punch above its weight, to borrow a boxing analogy. There is a place for both single blade planes and planes with sub-blades in the tool set, and neither type should be considered inferior to the other. This post series will also feature, for the first time on the Carpentry Way, a guest post by an experienced West Coast craftsman. I hope you'll stay tuned.

On to post II  ←← link

Tuesday, May 29, 2012

Bandsaw Jim Duggan


Anyone get the reference to the post title from the above picture? You'd have to be over 40 to have a chance I would think - pretty obscure.

The three phase motor I ordered from Hitachi Japan to replace the gear reduced single phase motor which comes with my Hitachi CB-75F bandsaw is not going to be making its way to my mailbox anytime soon. My Japanese hardware store contact, an old friend from Hokkaido named Hayase-san, made the mistake of actually speaking with someone at Hitachi about my motor swappin' plans and, when they learned the motor was going to be exported to the US, declined to sell the motor. Is this anti-US sentiment raising its head once again? No, it's much more mundane than that - Hitachi is wary of any lawsuits that might arise out of using a motor not specifically designed to run on 208v. 3-phase current. The fact that a 200v. motor would probably run just fine, at least fine enough for me to 'risk' it, is not germane to this matter. The Hitachi 3-phase motor is unobtanium from Hitachi Japan unless one resorts to subterfuge.

So, I took a look at the mounting plate for the current 110v motor:


As you can see it is a piece of 5mm plate with the motor bolted onto just a portion of the plate. I remembered from the parts diagram for this machine that the mounting plate is the same for both models and it is obvious the mounting plate has ready provision to mount either motor. The question is this: is the provided mounting pattern something unique to Hitachi, or is is a standardized pattern that other motors will fit? Of course, it is possible to adapt a motor to the plate regardless, either by drilling new holes or bolting a secondary mounting plate into position, but I was looking to see if there was a relatively simple 1-banana bolt-on solution which didn't require fabrication or modification to the machine.

I put a ruler on the bolt spacing to check - the width is 125mm between holes:





And the length the other way is 140mm:



These numbers seemed rather convenient. Nice and round. I also measured the output spindle of the gear drive and it measured 24mm. I did a bit of research and discovered that this combination of dimensions spells out a standard metric size of electric motor frame - the 'D90L' in this case. There are two versions of motors for the D90L frame, one turning around 1800rpm and the other something like 3450rpm. Given the size of the pulleys for the belts, with the pulley at the bandsaw's lower wheel being about twice as large as the pulley on the output drive end, and the target bandsaw wheel rpm of 900, it follows that the 1800rpm motor should be a more or less perfect fit. That motor is about 2h.p, or 1.5kw, and by miraculous coincidence the Hitachi 3-phase motor for this machine is also 1.5kw. Baldor and Leeson both make motors in the 1800rpm variety and there are many to choose from on the market, new, NOS, used, rebuilt, etc., so I'll be picking one up soon. Along with the new motor, I'll obtain a couple of longer belts and the specific belt cover from Japan (if the gods are willing). I'll also look into whether link belts will fit the drive pulleys.

I also obtained a Hitachi 6mm bandsaw blade, and fitted that onto the machine. The Hitachi guides were a bit fiddly to set up and are configured so that the bandsaw blade sits further inboard on the wheel tires than is suggested in the manual, but that's the only way it would work. The lower guide seems to have a mounting shaft which is slightly short and this means the blade has to be positioned further inward to meet it properly. It is what it is I guess. Here's the upper guide now set up:


Once I've run a bit of wood through it I'll know more about how well this all works.

I've also been on the hunt for a sliding chopsaw. Ideally, I'd like to get a large German made Graule ZS200N saw like this:


This company has no representation in North America, however I did see and use one of these on Vancouver island so the odd one has made it's way over. They're expensive. They're awesome. Maybe some day - some day when I have 460v service!

I considered a Northfield Unipoint saw:


In the end, I decided, in terms of resource allocation, that a consumer grade sliding compound chopsaw would do the job for the time being and would be something portable to take to job sites when required. And they are a whole lot cheaper than the industrial quality machines of course. I looked at Festool, Makita, Hitachi, Ridgid, Bosch, and Dewalt, weighed the apparent pros and cons, realized each of them would have both their good points and idiosyncrasies and flaws, and in the end chose the newish Dewalt DWS780 12" machine. I liked its relative simplicity (compared to the Bosch anyhow), large 19" crosscut capacity and the shadow light system looked intriguing. It was also $200 less than the Bosch and that sealed the deal. Here it is, looking for a home in my shop:


The white light around the bottom of the blade is what you get with the shadow light system turned on. it both illuminates the cut area and provides a cut line.

Another view:


I suspect that the blade that comes with this machine, like Dewalt blades in general, isn't the best, so I'll keep it for use cutting rougher material, and have ordered an 80T Forrest Chopmaster to be the main blade for use. I'll be mounting this up in a stand soon enough in my shop.

I was also looking for a tablesaw. My dream machine is out of reach for the time being, so I was considering a variety of options. One machine to which I gave a really close look, following the recommendation of an acquaintance, was this Tannewitz XJSW saw, built in 1961:


This saw has a sliding table (the 'S' in the model name XJSW), plus extension table (the 'W') and can accommodate up to a 20" sawblade. It weighs 1950 pounds.

The saw has a beautiful scraped ('flaked') top, and two different types of rip fences:


Unlike most older Tannewitz's, this saw had almost all the accessory  miter gauges, sectors, and so forth - even a factory brochure and machine blueprint:


I very nearly bought the saw, but in the end decided against it for a variety of reasons. I may change my mind on that, but I'll continue the search in the meantime.

I'm not going to be in the shop much this week as we have just finished moving house and have a mountain of boxes to sort through, and my truck has decided to call in sick with a rear wheel bearing issue. I've ordered the new bearings and seals for the repair and should have it back on the road by the end of the week. Fingers are crossed.

All for now, over and out. Your comment is always welcome.

Wednesday, May 23, 2012

Shop Vac: recently mobile

I had an informative conversation with a person at the Connecticut-based company Air Handling Systems, which specializes in parts and design for dust collection systems. That conversation led me to reconsider the set up I was establishing for my dust collection system, and as a result I moved the cyclone tower and bag house to the opposite side of my shop space. This new position allows for a straight piping run immediately into the cyclone, which reduces the possibility for turbulence in the air flow. It also cuts down on a few of the more expensive large size fittings i would have required otherwise.

I've now connected the cyclone and bag house together, and have made inroads on the 3-phase wiring for the blower motor. I thought I'd share a few pics:



This is my relocated planing beam and my saw rack is also in a new spot:
 

I'll probably expand the bench and storage arrangement in that area as well. Trying to keep a fairly clear open area for hand work and assembly despite all the rearranging and added equipment.

It is looking like I'll have to drop another $900 or so to get all the pipe and fittings I need to complete the system, which is a bit more than I was imagining it would be, however the system was so inexpensive to begin with that I'm still ahead, it would seem, on the deal. I'm going with industrial grade spiral reinforced duct piping and all metal fittings and will be able to re-use about 50% of the piping and fittings that came with the package. The duct work design is complete and I will likely place the order for the fittings tomorrow.

Thanks for visiting. My shop is in a bit of flux at the moment but in another week or so I should be able to start working wood again. I might have a new (used) machine by this weekend to add to the mix.

Monday, May 21, 2012

Shop Vac Review

I thought the title of today's post a little humorous considering the 'shop vac' which arrived today on three skids:


The bag house on the right has 30 slim bags in it and two metal pull-out drawers on the bottom - the bags were disconnected from the bottom plenum so extra stuff could be crammed in there. It took quite a while to unpack all the bits:


As you can see the system, made by Air Sentry, was originally green but was repainted at some point. Here's the chip bin with it's pull out box on rollers - this bin supports the cyclone:


An interesting assortment of piping came with the machine:


Some of the piping was even bigger than the inlet pipe to the cyclone, leading me to wonder if the original system was even larger or if there were two systems as some point:


Getting the cyclone, which must weigh around 300 lbs., on top of the chip bin was entertaining - we (my shop neighbor Joe gave me a hand) used a come-along attached to the floor joist above to ratchet it up into place and then bolt the two parts together:


The 7.5 hp. Baldor motor was also quite heavy and required winching up to mount atop the cyclone. Total height from floor to top of motor must be close to 10 feet.

The piping puzzle gradually gets sorted out. I'll inevitably have some pieces I can't use, and will need to buy a few more pieces to put it all together:


Included in the system were a couple of nice fabricated sheet metal collection ports, like this one:


There is also a floor pick up vacuum opening, and even a large downdraft sanding hood, which I have no use for:


I imagine I'll be able to find a buyer for it somewhere down the line.

A dusty day, but i was pleased with the system I brought into my shop for less than $1000.00. I'm sure i'll have to drop another $2~300 on it yet to get it working. I plan to get the wiring sorted tomorrow and connect the bag house and cyclone together. It will be sweet to finally have a dust collection system - better for my health obviously, less mess to clean up, and the few machines I use should work a bit better as well.

Thanks for dropping by the Carpentry Way.

Friday, May 18, 2012

Papa Bear and Baby Bear

Now that my newly-acquired CB-75F takes its place next to the CB-100FA on the right, I must admit it really is a cute li'l unit:


The front side of the CB-75F:


It's in pretty good shape and worth the $1000 investment.

I didn't realize that the CB75F has rubber tires on its wheels:


The rubber tires mean fitting other size blades is totally straightforward - I had been wondering about this detail before the machine arrived.

With the rubber tires you get a brass bristle cleaning brush instead of the steel scraper as seen on the CB-100FA with its large cast metal wheels:


The guides are meant for a 3" blade, however the machine as received had a 1" blade fitted, which doesn't really work properly with the regular guides, gouging out the middle:


The blade-tensioning mechanism rides up and down on dovetailed ways, and these are provided with oil cups on both sides:


I plan to use this machine to run 1/4" (6mm) blades most of the time, and have acquired the factory ball-bearing guides for that conversion:


The guides took all of 5 minutes to fit - a drunken chimp could do it, so I was well qualified. Now I need to get a 1/4" bandsaw blade or two. Any recommendations? I've ordered the 3-phase motor and its associated parts from Japan so I should have them in a few weeks. The machine runs fine as is but the 110v. single phase motor with gear reduction is going into early retirement, despite the, uh, howls of protest.

Thanks for visiting!

Monday, May 14, 2012

Buy Sell and Trade

The past couple of weeks have seen me between phases of my current project and it has been nice to have a break. My wife and I are moving into a new house so it hasn't been entirely restful and the weather hasn't been cooperating with my plans to take the mountain bike out, but, oh well.

I'm in a position to acquire some new equipment for the shop, and any interesting bits of wood I might come across, and I have been indulging. Well, mostly window shopping actually. This is a great time to be looking for equipment as it is definitely a buyers market and lots of machines are available. Curiously, when the economy is flat, the wood supply tends to dry up as log suppliers see little benefit in sawing their material up and dealers prefer to clear out old inventory and remnants rather than bring in new material. So, the wood scene is a bit of a bust though I have in fact found some pretty exciting bits of timber which I'll possibly write about in the near future.

On the machinery front I decided that I would sell the Multico Hollow Chisel Mortiser as I just wasn't making any use of it. I have a Powermatic that I use and no real need to have two machines. So I managed to find a buyer for that, at $500, and I am looking to put that money into some other piece of equipment. Not sure quite what that will be yet.

I put my Oliver 166 belt drive 16" jointer up for sale as well. It's working fine, but I would like to make the jump, if I can to the next level. The next level in jointers, from my perspective, is something 20" or wider, preferably longer than 8', and with a 4 knife Tersa head. There are a few used machines out there which might do the trick, however I need to sell the Oliver to be able to make the move. Besides, a small shop like mine only has room for one aircraft carrier at a time. If the Oliver doesn't sell, I might consider swapping out its cutterhead for a Tersa or Shelix. I recently obtained a 4" Shelix head for my shaper, along with a rub collar, and it works nicely. I'm not totally sold on the insert knife helical heads however.

One of the less glamorous pieces of the shop which is however absolutely essential is a dust collection system. I have found it hard to get particularly stoked about buying a dust collection system - you might say they suck wind - however that all changed when I came across an interesting deal on Ebay. Out in Illinois there was a High School with a wood shop. The funding was eliminated for shop programs in that part of the state (a very sad sign of the times happening all over the place), and they were going to convert the shop into a weightlifting gym. Gotta give the football team something to play with I guess. The shop had a nice dust collection system in place which had to go. It's a US-made Air Sentry system, 7.5 hp, 3-phase, with cyclone and baghouse. All metal piping including shrouds for a chop saw, downdraft table, floor vacuum pickup, etc., etc.

Here's a few pics of the parts - the baghouse:


The cyclone with chip bin:


Some of the duct work:



When I first came across it, the tarting price was $1000, which was pretty reasonable. However the logistics of picking it up and getting it back to Massachusetts seemed a bit much to deal with so I simply kept an eye on the auction to see what the set up went for. It didn't go for much as no one bid. Then the seller re-listed it on short auction format, start price of $100.00(!). Suddenly, as you might imagine, I was rather more interested, and made contact with the seller and found that time to sell at the school's end was at a premium, that the gym renovation was underway and that the system was already partly disassembled. They needed it gone. The seller indicated he was in fact willing to package it all up and put the pieces on pallets, so I made some inquiries with my shipping agent and obtained a price of $299 to move three pallets of 500lbs. each. Now we're talkin'!

I had some late minute turbulence on Ebay with the snipers at auction's end, but when the dust had settled I was the highest bidder at $611.25. That means with shipping included I will have a great dust collection system for under $1000.00. How cool is that?! It is all to be shipped the middle of this week so I should have it by the beginning of next week. I imagine it will take a few days to set up, and I'm very glad to have dust collection at long last.

-------------

I've also been looking for a smaller bandsaw. While my Hitachi CB-100FA 4" re-saw is a superb machine, I can't use it for anything other than re-sawing and thus something capable of running smaller blades was on my shopping list. Up to this point I've been cutting curved templates and roughing out parts using a hand-held electric jigsaw or making use of my neighbor's Jet bandsaw.

There are plenty of smaller bandsaws out there, most of them imports, but by and large they tend to suffer from a common problem: the chassis and/or tensioning spring aren't adequately stiff enough to properly tension many bandsaw blades. While there is no shortage of monster antique US beasts, like the Yates, Oliver, Northfield,, American, etc., that perform well, I really didn't have the room, and wasn't interested in another rebuild project either. There are some decent Italian bandsaws, like the ones made by Agazzani and Mini-Max (a budget brand for SCMI), however I was thinking that I didn't want to drop $3~6,000 on a saw which would not see daily use.

I came to a solution though that I think will work really well - I'm buying the little brother to my CB-100FA, the CB-75F:


This machine weighs about 350 lbs, and is equipped with a 3" Stellite tipped re-saw. Now, the classic issues with this saw, as it was sold in North America as least, revolve, literally, around the motor. Presumably to make the saw more attractive to a wider consumer base, the saw was equipped with a 110v. 2.8 hp. motor. This motor is of the geared reduction type. This means the motor itself spins at high speed, and the splined output on the end of the motor shaft then turns a second larger gear. Here's a picture of the set up on the CB-75F:


You can see the small gear machined onto the end of part #251 drives the larger gear #260.  Gear #260 is in turn connected to a shaft which spins a belt drive pulley.

This gear reduction allows a small 110v. motor to power a larger bandsaw since one of the benefits of gear reduction is that the motor doesn't have to work as hard to spin the wheel. The torque produced by the output is inversely proportional to the amount of gear reduction. Problem is, the 110v solution, gear reduction not withstanding, is really a marginal power plant for this machine - certainly if much re-sawing is intended, though some people have reported satisfaction with that aspect. Worse though is the side effect obtained by gear reduction: the motor howls like a banshee and the gearing adds more noise. Not the most pleasant thing, especially in light of how quiet most bandsaws are by comparison.

What led me to select this bandsaw, despite the apparent shortcomings is this: unlike the CB-100FA, the CB-75F can accept smaller blades. There is a factory option to fit a set of roller bearing blade guides. Since the chassis of the machine is engineered to properly tension a 3" wide re-saw blade to 16,000 lbs., the unit will be more than adequate to tension a 1/4" or 1/2" blade.

And the motor? Well, that simply has to go. Interestingly, Hitachi sells this machine in Japan (and other markets, just not the US) also in a version with a 3-phase motor, with no gear reduction. That means it would be a lot quieter and more powerful. Here's a picture - compare the appearance of the motor with the one shown above:


I have made inquiries to some Japanese contacts to see what a Hitachi 3-phase motor might cost. If that's a no-go for some reason, I'm confident, based on the parts diagrams I've looked at, that re-powering this saw with another motor will be quite simple, though not an inexpensive endeavor. It will require some combination of motor and pulley, possibly a VFD, to obtain a running speed of around 900 rpm.

The CB-75F that I bought is in excellent condition, included extra blades, and cost me $1000. I found it in Maine. It will be shipped to me this week.

Finally, I was having some email exchanges with the fellow that bought my mortiser that led me to investigate a Griggio TRC-N mortiser, which is of the slot-mortising variety:


Unlike most slot mortisers, the head on the Griggio moves instead of the table. An interesting design.

I had a funny feeling when I looked at it that it was vaguely familiar. Later, I was browsing Martin's site and discovered something surprising:


I was most surprised to discover that the maker of the most drool-worth equipment in woodworking is now re-branding stuff made in Italy. huh. Nothing wrong with Griggio, but it is a notch below Martin. I did a little more looking at Martin's new 'basic' line of sliding table saws and discovered more of the same. Here's Martin's new 'basic' saw, the TC 640:


And here's Griggio's Unica 350:


Now I'm curious to learn how they might compare for price - that is, how much more would one likely pay for the Martin badge and paint? Hmmm...

Okay, well, that's a stroll through the garden of Tool Land for today. When I get the bandsaw I'll do a blog on swapping the motor over as I imagine some readers might find that of interest. Thanks for coming by the Carpentry Way - comments are always welcome.

Saturday, May 12, 2012

The Story of the Gazebo (VIII)

One of the funny things about drawing in 3D is that while it can often help with visualization and problem solving, sometimes you really need to be able to set things up in 2D first. Case in point is the curved eave layout on this pentagonal gazebo roof I am doing as a design exercise. With hip roofs, the eave projection and rafter spacing are directly tied, and in Japanese carpentry practice one of the crucial aspects to getting a hip roof right revolves around getting the common rafter spacing sorted just perfectly. And with a eave that curves up, and a hip rafter curving up, the length of the eave changes from what it would be if the eave edge were straight.

It was in trying to move my drawing along a bit by adding in the soffit paneling that I discovered a problem with my 3d work. I had drawn the curved eave as a 3D construction in the first go-round, and the defects that arose because of this took a while to manifest. It turned out that I had so make a slight adjustment to the eave projection to correct the problem. So, it was back to the drawing board, and this time starting in 2D:


The projection traces, which are numerous, have been stripped away from the drawing to show it a bit more clearly.

With the 2D plans of the pieces figured out, I was able to construct 3D pieces from there, now including the soffit paneling and lattice (komai). Here's how that looks at this stage:


A view from underneath - at this point the material coloring is temporary and I will likely be making some changes before long:


There will be another soffit/ceiling, fitted between the wall plate and the outrigger plate, and I haven't started to draw that yet.

On top, I have roughed out the hanegi, the bowed cantilevers which support the eave:


So, it's moving along. At this point the hanegi are perhaps a little too thick, but their shape is about right:


Next up are the fulcrum beams for the hanegi, plus other framing details which associate, and then I will start on the lantern support framing and work out the actual roof profile. At this point I am thinking the roof surface will be moderately campaniform (bell-shaped, ogee-shaped).

In other news, I have been doing a little shopping for tools and wood and have a few new 'show and tell' items to post about in the near future. The Carpentry fundamental study group is on the cusp of starting project 2, which will be scissor-braced sawhorse. New members are welcome to join at any time.
 
Thanks for coming by the Carpentry Way.