Saturday, November 21, 2009

Chair 2, part 3

So, this afternoon I did a lot of shaping of parts, and got the chair glued up. There were some parts of the process that weren't pretty, but it all came together.

I'm not always the most patient guy when it comes to seeing any kind of end result, so I clamped a board across the underside of the chair, to see how it felt when I sat down. Now, just having a board clamped across is not a fair estimation of a finished seat cushion. But it did give me a few insights into how the chair will feel when it's finished. For a second try, it's already several steps in the right direction away from the first one. I still have a lot of shaping and smoothing to do, but the way the arms splay out makes the chair feel less constraining. The seat is deep enough, and the way my knees fold around the front edge just feels right somehow. And the back is lower, and feels more supportive... but it's not quite where I want it yet, I think I actually want it a little higher, so there will be a third version, at least, before I start trying to do batches of these things.

So, I sat back, let the glue dry, took some notes for future reference, and then went to turn a bowl on the lathe. It's been a while since the last time I played around on the lathe, and I will say it was fun, for a while. I had a small piece of walnut that had some curl to the grain. I managed to scrape out a decently shaped bowl, with walls that were thin enough, considering my serious lack of experience with bowl making. I got the finishing process started on the inside, and I was pretty close to being ready to flip it over and finish the underside. Then the capacitor for the motor blew out and ruined all the fun. I was less than pleased. It's not catastrophically bad, it's certainly repairable with a minimum of real effort. But still, the lathe is down, and the bowl remains unfinished.

Given that it's the week before thanksgiving, I imagine the rest of the world will be pretty quiet, so I foresee a good couple of days in there this week. So there will be more to read about, soon.

Friday, November 20, 2009

Quick sketch of hard clamping in the Veritas twin screw vise.

So, I mentioned about 2 weeks ago that I would put up pictures to describe what I was talking about, when I said that it was possible to use the vise to really crunch down on something. Rather than re-edit that post, I figured it would make sense to do it this way.

Step one:

Put the object to be held into the left side of the vise. (Or, the side that does NOT have the release pin on the handle.) Both screws will rotate inwards, as shown.

Step two: Pull the release pin. This will allow the handle on the right side to spin freely, while the left side still holds with regular clamping force.

Step three: Rotate the right handle as if to loosen the jaw on that side. Because of the way the vise is built, it will actually lever the right side of the jaw out, a little bit, pivoting around the left hand screw. The force it gets from using the length of the vise as a lever will really crunch down on whatever's being held in the opposite side of the vise.

This isn't always truly necessary, but once in a while you get an oddly shaped object that you have to saw through, or do something else that exerts a lot of force. When it comes to that, there's just no substitute for the application of fundamental physics.

More chair work

So, last night I felt like a complete fraud.

I had figured out, or so I thought, how I wanted this chair to go together. I ended up having to work through so many hack-shop crazy ideas on how to combine random pieces of wood with a crosscut fence, running it all backwards past the table saw blade... in the end, it all worked out. Chair came together. But I have to say, throwing in odd angles into a chair, and then trying to make them all fit together in three dimensions is a hassle.

I guess maybe I feel like I should look and sound as confident as someone on TV, that everything always goes to plan, and I always know exactly how things are going to go... and I'm not always that confident.

Then again, this is my first attempt at trying to build a chair in this particular way, so I guess it all works out.

Thursday, November 12, 2009

Monday, November 9, 2009

More chair work... Prototype II.

On Saturday I went in and got some more work done on prototype II. Front leg joinery is done, back leg joinery is done, and I proceeded on to making a back support piece from there.

Have you ever made a mistake, thought about why you made it, and then immediately repeated your mistake? Well, I did.

I saved a chunk of the beam and left it full-thickness (about 3") to allow a lot of room to shape a big, comfy hollow into it. I measured the distance between the back legs, across the back, and cut the piece to fit. It did fit, but it was actually projecting forward, instead of backward. I wanted the hollow to extend back behind the legs, so the tops of the legs could be part of the support.

So, I took one of the spare pieces that I had lying around and repeated the cut. And, I got the same result.

The root of my problem stems from the fact that the back legs on this version come away from the back at an angle. I figured that, if the tops of the back legs curved back enough, that angling the legs outwards away from the seat would also allow that curve to widen, instead of having the legs come up parallel to each other. I was more or less right on that score, but I do need to make the curve a little stronger in the end product.

Back to the seat, because the legs are at an angle to each other, the back piece also needed to be cut at an angle to be able to join to the tops of the legs properly. In essence, there's a taper, growing bigger from front to back. Since I measured the back piece to fit the largest space, it went all the way in. Had I measured it to fit to the shorter space, and taper outwards from there, it would have been fine on the front, and been able to curve backwards from there.

The solution this time around was to resaw both pieces that had been cut wrong, and glue up a block that will curve back as I need it to. The solution next time will be to not screw it up again.


In other news, the hunt for a viable day job continues, as I work part time to get these prototypes worked out. Eventually, I plan to move (hopefully) back to full time, once I work out the details of the final product(s), marketing, business planning, and things like that. But I think it's going to be a while getting there.

I have to say, it's a hard thing to look back. A year ago, I wrote a post about the failure of my first shop in Medford. I thought I understood where I'd gone wrong as a woodworker. (Insert wry grin here.) This is a paragraph, pulled from this post, about the failure of my last shop.

"From Failure we learn; Success, not so much." The challenge for me right now is to allow the failure part to sink in, so that it's appreciated properly. Blindly going forward with my chin up and a can-do attitude is all fine and good, but I really need to figure out a few more things to make sure that this next try doesn't end the same way.

So, I worked out my woodworking failures. I can say I'm a lot better at being directed and organized when it comes to building things. But I still went blindly forward, chin up, with that can-do attitude. I think this is actually a virtuous thing. And I even think that being willing to do it blindly can be worthwhile, since I can say now that it's not always possible to see the cause of our next failure or problem. It's a process, and the important part isn't to not get knocked down. It's to remember to get back up. But being willing to run blind is different than willingly running blind.

I think my failures thus far, business-wise, come back to something that I knew early on, and forgot for one reason or another: People really like buying concrete objects. I.E. 'Would you like to buy this __________ from me." (Insert chosen object of furniture; chairs, tables, etc.) People will then either say yes, or no, or "I like it, but I want this to be different..." So, 2 of the three options are winners... because I'm not a production shop, I can alter things to cater to personal requests.

I hadn't developed many products to sell, aside from my portfolio pieces from school, and a class or two. Kind of a dumb move, in retrospect. "I can do whatever," is not an inspiring or convincing sales pitch. Doing my homework and coming up with a better plan before setting fire to a pile of money would have really saved me a lot of heartbreak.

I'm paying the price for that right now. It's my failure, I earned it. So, the project right now is to do more homework: Come up with a new plan, and a concrete end product to sell, and a plan to market and actually sell the thing. I'll be working a day job while I do this, and work in the shop when I can. Step one is to get the woodworking thing to pay for itself. Step two is to get the woodworking thing to a point where it can support me.

In the meantime, the days are getting shorter, and it will soon start to get cold in the shop. 

Saturday, November 7, 2009

Veritas Twin Screw Vise... My modifications and supplemental user's manual

Heads up to the reader: This will be one of those technical entries that's up for the sake of posterity, but will be incredibly boring and irrelevant to anyone without this particular piece of equipment. So feel free to skip this one and move on to the other postings, which will talk more about chairs, and shop stuff.


This afternoon I was in the shop working on chairs and trying to mount something in the vise. But the problem I've been having with this particular vise is that both screws have been turning independently of each other.

Mechanically, the root cause for this is grub screws that aren't able to bite into the shaft of one of the screws. The left handle is pinned through the end of the screw shaft, but behind that, there's a gear that drives/is driven by a chain. The gear on this side clamps to the shaft using 2 grub screws, oriented at 90 degrees to each other. The chain goes around this gear, linking the left screw to the right screw. The right side has a similar gear, but the gear is hooked directly to the handle by way of a retractable pin. The pin is there to allow the two screws to operate independently, within a small range. All things being equal, this arrangement would work out fine. But, all things are not typically equal, and the issue here is that the retracting pin is a stronger mechanical interface than 2 grub screws. (Thin as that pin happens to be, it's still a better lockup than friction.)

The other root cause of my issues is that I'm simply stronger than the average guy, and I've been known to really crank down on the vise from time to time. The result is typically the same... something's in the vise, and both sides need to be individually tightened... and as a result, the grub screws scrape a little bit around the shaft. Repeat this issue a few times, and there's a small groove around the shaft, requiring that I remove the chain cover, and re-tighten the screws. There's an access window to do this, but it's a dumb idea. My logic is this: The screws should really only be tightened when the vise is actually aligned. And the best way to align the vise is to clamp it shut, tighten both sides equally, and then secure the screws where they are.

Well, eventually I tired of all this nonsense, and simply let both screws turn independently. There are certain advantages to using the vise this way, but the truth is that really, it's just better to use the thing as it's designed to be used.

So, I pulled it apart again today, and fixed the problem once and for all.

Famous last words...? Let's simply say that I have modified the vise to alleviate my issues, and pending further notice, it's working a lot better... but there are specific techniques that bear mentioning.

After removing the cover and aligning the vise per usual, I took one of the grub screws out. Using a transfer punch, I marked the location of the hole on the shaft. I then disassembled everything on the end of the shaft... Handle yoke, gear, and Jaw plate all came off. I then drilled an indentation into the surface of the shaft, to make a socket that the grub screw can mate with, and that will give more purchase to the screw. I put the gear back on, tightened the screw in place, and marked for a second indentation for the second screw. Removed the gear, drilled the shaft, and reassembled everything.

What I should have done in retrospect is used thread lock, too... but I'll do that another time if the gear develops any slop.

What I also should have done is taken better pictures, but it didn't occur to me until afterward that this was worth putting up, so the best I could do was to remove one of the grub screws. You should be able to see the socket I drilled out by looking through the hole where I removed the screw... if you click on the picture above.

In theory, this modification will give the grub screws a mechanical hold, and not just a friction hold, on the shaft. And, in theory, this end will now have a much stronger lock than the small sliding pin on the other handle. The pin is fairly small, and I've heard stories of them breaking... which is probably why a spare pin is included.

So... new vise operating procedures.

Now that the gear for the left screw has such a stronger lock on the shaft, I think it's a safer bet to use that one to tighten the vise with. The risk is that I'll tighten too hard on the right handle, and shear the pin.

So, from now on, I'll do most of the holding work towards the left of the jaw, and tighten with the left handle. The right handle should be able to follow along perfectly well, and it still has the crank handle for quickly running the jaw in and out.

Last technique, one I figured out while running each screw independently... It's possible to exert a lot more gripping force on a board (or anything else) outside of the left hand screw. (As opposed to using the space between the screws) I set up the object to be held, to the left of the left hand screw, and tighten the vise down normally. Then, I thread the right hand screw counterclockwise to move the right side of the jaw outwards. Basically, I'm using the width of the jaw as a long lever, pivoted on the left hand screw. This technique is NOT good for massive movements, and certainly not good for holding tapered work, because the design of this particular vise doesn't really allow for that. But disengaging the sliding pin on the right handle will allow the gear on that side to disengage completely, so the right hand screw can operate independently, and lever the right side of the vise outwards just enough to add a lot more pressure to whatever's being held.

(A more visual explanation is here)

Other modifications:

I made a few small design changes to the way I installed the handles. First, rather than drilling all the way through for the crank handle, I installed a threaded insert in the handle. I just think it looks cleaner. I had to shorten the crank handle bolt accordingly, but that was pretty simple.

Second handle modification. I noticed right away that using the crank handle means locking the handle in place so that it can't roll. There are brass thumbscrews that come threaded into each handle yoke, but I knew right away that these would have issues keeping the handle from spinning if they were only being used on the surface of the wooden handle, with the end result of a scratched up, screwed up looking handle, and an ongoing difficulty in using that crank handle. So, I drilled a hole in the center of each handle, and inserted a brass shelf pin socket. I think they're made by Vertex, or one of the other premium brass hardware suppliers. These sockets have holes drilled in them that are 1/4" in diameter, which fits the brass thmb screws very well. They do a great job of keeping the handles secure, and they keep the crank handle from rotating the right handle around. AND they look a lot nicer than simple holes drilled in the wood, which would most likely wallow out over time.