What's your tolerance?

[toddlajoie]

OK, so I've got about a million questions on the finer points of turning/sizing, mainly with turning between centers using calipers and finishing with CA.

Let's say for example, your kit hardware is 0.470, what would you do?

1. Turning with tools, gouge, skew, etc. What measurement do you go to with the tools?

2. After that, sanding, roughly how much thickness do you expect to loose to sandpaper?

3. How thick do you build up the CA to?

4. What range are you happy with in the final size measurements?

I'm wondering if I'm being too anal-retentive in getting EXACTLY to the kit size.

Here's what I've been doing so far, based on the same 0.470 hypothetical kit size.

1. Tools to around 0.475

2. 400 grit sandpaper to right around 0.470

3. 600 and 800 grit sandpaper to around 0.465

4. Medium CA, usually 10 or 15 solid coats, back up to 0.480

5. Several hours of rest for the CA to fully harden. This is usually either overnight, or over the work day...)

6. Skew back down to around 0.472-3, and check for any deep ridges. If there are, go back to step 4 and repeat.

7. Micro-Mesh to 12k and Plastic Polish.

The results on this are fantastic, but the time is killing me. Building up that much CA takes a bunch of drying time and I'm wondering if I'm wasting effort trying to get within 1/1000th of the kit measurements.

I'd love to hear the details of anyone else's procedure...

 

[NewLondon88]

Mine is a little less methodical.

I measure the bushings first, to see if they match the kit parts. If not, I discard
them and use another set.

Then use my roughing gouge till the material is almost there.
I 'measure' it by rubbing my finger along the bushing and onto the material. If
there's too much of a ridge, I turn away more. I sharpen the roughing gouge on
a belt sander with 220 grit, so I can get a pretty nice finish right off the gouge.
I can start sanding with 400 most of the time. (or on resins, start MM at 1500)
When I can't feel the transition from material to bushing, I'm good. if I'm going to
use CA then I'll sand a little further and build it up with CA.

That's about as close as I get to a routine.

 

[IPD_Mrs]

Let's say your kit hardware is 0.470, what would you do?

1. Turning with tools, gouge, skew, etc. What measurement do you go to with the tools? Would turn this down to about .0470 to .0467
2. After that, sanding, roughly how much thickness do you expect to loose to sandpaper? This would take me down to between .0463 and .0465 Hopefully closer to the .0465 - .0466/7 range if I was able to take the blank right to the bushings to start.

3. How thick do you build up the CA to? Starting with some thin running about 6 coats with kicker in between each one (a few seconds to one minute of addtional dry time after the kicker on each coat) Then if that looks good and there are no obvious defects that would require removing = 6 - 10 coats of Medium CA done the same way ... Kicker in between each one with a little longer dry time but no more than 1 - 1.5 minutes I would guess. ..

When all is said and done I would like the blank at this point to be somewhere around ..0475 ok if it is within .0475 - .0477.

AT THIS POINT WE START SANDING with the Micro Mesh. There is no reason that I can think of to need to take off the finish with the skew UNLESS there are obvious flaws in the finish that you need to remove.
4. What range are you happy with in the final size measurements?

I am happy with a perfect fit. In your hypothetical situation I would be caliper measuring for a finished product of .0470

That doesn't mean, however, that I am going to take off the finish and start over if my caliper says .469 and the finish looks like the Hope Diamond that I'm taking it off. I will put it on the pen and see how it looks. If the fit is REALLY off and looks like I am going to have trouble selling it then I am going to disassemble (use the proper tools) and redo - otherwise most people that are not in the pen making business are not going to notice a 1/1000 difference.
I'm wondering if I'm being too anal-retentive in getting EXACTLY to the kit size. Well not in my book, but apparently I am as anal retentive as you.
I will say - if the space between the wood and the fittings is too large - or appears to be large - it may put off some people as they will feel it when they run their hands over their pens, and it will collect oily dirt and grime from every day use. Personally, I don't want someone showing off their pen with it looking bad from use and then giving my name out. I prefer positive publicity :tongue:
Here's what I've been doing so far, based on the same 0.470 hypothetical kit size.

1. Tools to around 0.475

2. 400 grit sandpaper to right around 0.470

3. 600 and 800 grit sandpaper to around 0.465 Note we are using 220, 320, 400 and 600 grit sand papers.

4. Medium CA, usually 10 or 15 solid coats, back up to 0.480 As above we are using a mixture of thin and medium

5. Several hours of rest for the CA to fully harden. This is usually either overnight, or over the work day...) Kicker will solve this problem.

6. Skew back down to around 0.472-3, and check for any deep ridges. If there are, go back to step 4 and repeat. see above

7. Micro-Mesh to 12k and Plastic Polish. Not sure what plastic polish you are using we use Novus 1, 2 and 3. Sometimes we skip number 1 and use the Renaissance Wax.

The results on this are fantastic, but the time is killing me. Building up that much CA takes a bunch of drying time and I'm wondering if I'm wasting effort trying to get within 1/1000th of the kit measurements.

Well time spent pursuing perfection is time lost in enjoying that which dances around you.
However, as a perfectionist myself - if 1. you are enjoying what you are doing, 2. you are doing it at no cost to the others in your life, 3 you are meeting your goal for this hobby - then you are not wasting your efforts or time.

...

MRS

 

[Craftdiggity]

My process is a lot like Charlie's, although I usually have to start sanding at 150 or 220. I use good bushings and I can usually feel when I have it right with my finger. I use thin coats of CA and sand every five coats or so until I have the finish I want. So far so good. My fits have been right on. Knock on wood...or resin. Whatever I am using.

 

[soligen]

Todd,

My process is about like yours, and yes it is time consuming, but I want the results of a fit that is right on. I'll accept a couple thousandths off at the finial, but I want the nib perfect because fingers will feel it if it is off.

I'm just as slow at this as you, but hope it will get quicker with practice, but I figure if I back off on the standards, then I wont learn how to get really good results more quickly.

Here is where my process differs a little.

I dont use the skew on finish.
I use all thin CA for my high gloss finishes.
I use white diamond buffing compound instead of plastic polish.
I only wait until the next day for final buffing.

I take the barrel off the lathe and test fit it to the part - press it in to check then knock it out (cover the part with blue painters tape when you knock it out to protect it as it falls free). If the fit isnt acceptable, I keep working on it. Note that Accurate meansuremetns are not easy to take, and you have to trim the CA "rollover" to get a good measurement too. I also think that pressing in a part can expand the tube a bit if the fit is tight, so the measurement may change after the first test fit.

As for time, yes, I've spent hours on the finish just for one pen. Time consuming but I am getting better.

 

[workinforwood]

I have no science at all. I turn the blank down to the bushings. I remove the bushings and mount the blank between centers then remove an additional gnats hair amount. I apply finish. I sand and polish the finish. I check the blank and hopefully it is perfect or else just half a gnat hair above where it needs be. If it is just barely larger than need be which is what I generally hope for, then I do a quick light chamfer on the ends. I prefer my pen to be just the slightest smidge oversize with the slightest chamfer possible because it gives a nice transition. Undersized to the parts is un acceptable no matter how little because you can then feel the sharp edges of the pen parts.

Out of Round..that's the main thing...pen must be perfectly round as possible and that makes everything else work out for the best.

 

[bitshird]

I have no science at all. I turn the blank down to the bushings. I remove the bushings and mount the blank between centers then remove an additional gnats hair amount. I apply finish. I sand and polish the finish. I check the blank and hopefully it is perfect or else just half a gnat hair above where it needs be. If it is just barely larger than need be which is what I generally hope for, then I do a quick light chamfer on the ends. I prefer my pen to be just the slightest smidge oversize with the slightest chamfer possible because it gives a nice transition. Undersized to the parts is un acceptable no matter how little because you can then feel the sharp edges of the pen parts.

Out of Round..that's the main thing...pen must be perfectly round as possible and that makes everything else work out for the best.

I'm with Jeff on this method, A smidge .001 to .003 over size on the barrel and chamferd feels good and the transition isn't noticeable to a customer, I haven't had any carry Micrometers or Calipers and check the fits when buying pens.

 

[fernhills]

Try as i may, i can not get the same caliber measurement twice. So i get it there and i shoot for just a smidgen above the hardware. I take it off the lathe and check the pen parts aganst the blank. Most causes for it to be pressed in to tight, is, there is something in there. Carl

 

[IPD_Mrs]

I'm with Jeff on this method, A smidge .001 to .003 over size on the barrel and chamferd feels good and the transition isn't noticeable to a customer, I haven't had any carry Micrometers or Calipers and check the fits when buying pens.

Perhaps no one carries Micrometers or Calipers - but I have run into some that carry 30x jewelers eyes. They can see the fit just fine with those. :wink:

 

[toddlajoie]

Thanks for all the info/feedback/advice everyone.

Charlie/Chris/Jeff/Ken, I got sick of keeping track of of all the different bushings, so I've been working on turning everything without bushings between centers. I'm a bit of a spaz with sandpaper also, so within 2 or 3 pens, my bushings were always "low ballparks". Yours an other methods were the way I did it previously when I was using a mandrel (another spaz on my part, always overtightened, and soon OOR shows up to **** me off...) In the end, even when things went well, I usually ended up either over or under size... I guess I just don't have the "feel" for it.

(Side Note: Jeff. Picked up one of your super cool dragon blanks from exotics, the thing is beautiful, and it's going to take me some time to get up the nerve/time to turn it. Bought it as a gift for my son when he gets his Black Belt in TKD, which is probably going to be January... so I have a few months...)

Linda/Dennis. Nice to hear I'm in the ballpark with some others. The method seems logical to me, I was just wondering if I was missing something. I was actually playing today with accelerator, and it does help (and I learned that if you don't give it that minute or 2 after applying, you can get some separation when you trim the edge roundover....) I have tried thin CA in the past, but I must be too slow, it usually hardens either before I get to the blank or soon after I touch it, bringing the paper towel with it... So thanks for the advice, but I'm going to stick with Medium for now.

Carl, Most of my measuring time is spent trying to get the calipers right on the edge of the blank. I can typically get the same (+-.001 or 2) measurement 3 out of 4 times, and the 4th is usually off by so much that I know that I missed the edge of the blank... I've also tried press fitting parts then dis-assembling, but I've found that the second time I assemble, often the parts are too loose, so I'm trying not to do this...

Again, thanks for your input. I've got 2 sets of Johnny's bushings, and those kits go a good bit faster, since I can get a lot closer to final size before the calipers come out. Going to have to save up for some more, or cut down on the number of different kits I do.

 

[soligen]

I've also tried press fitting parts then dis-assembling, but I've found that the second time I assemble, often the parts are too loose, so I'm trying not to do this...

I have had this happen too. Actually I've had 2 woodcraft kits that were too loose on the first fitting. Blue loctite holds em good.

 

[johnnycnc]

My random thoughts on some of what you are asking..
I do not use calipers, at all, when making a pen.
Using bushings of the right size and taking the blank to a relative size to those
bushings at different stages; turning sanding CA finish, etc. is all done by feel for me.
Try turning a little closer, and finer, and you won't have need of going spaz, as you say, with the sandpaper.
I can get 50+ pens off a set of my bushings, and yes, I sand! just concentrate on the blank, and remember you don't need to sand the bushing.

The final barrel in my mind is like Jeff and Ken said, a hair proud of the kit parts
and never below.
I use calipers and micrometers on my job, and knowing when such tools are necessary
for a job, is part of my job. I do not use them for instance when sawing a piece of stock off, I use a tape measure or scale.
Match the tools to the job, and your end requirements.
I think the calipers can be useful for some folks if they want to use them, but I have never had much desire or need to do so.
Turning between centers with no bushings and calipers is ok I guess if you have tons of time, I never had any luck getting the blanks to hold firmly enough to use turning tools
effectively. They always stalled out until I muscled the centers tight enough to wedge things. But, to each his own on that.:biggrin:
As for 10-15 coats of medium CA.. I think you would be just as happy with half that or less. You may need to improve your application so it's not so rough as to need cut back with a skew. I use 1-3 coats thin, 1-2 coats medium and start sanding no coarser than 400, then onto micro mesh.
Out of round will drive some to build up a huge layer of ca so they don't cut through, but if you are not out of round, I'd ask myself.. is it really needed?

John
♠

 

[JimB]

Don't laugh now... but I don't measure anything. I turn it down to the bushings and do some sanding and run my fingers across to see how it feels. Then I remove the bushings and sand a bit more between centers and MM to 12000. Then finish with thin CA or Poly. If I did all that measuring I probably wouldn't be having any fun.

 

[Spats139]

After I started using calipers (based on suggestions on this site) I found that the fit of my pens improved because I wasn't trusting the bushings anymore; and the biggest problem there was that I had worn my favourite bushings down to a point where I shouldn't have been trusting them any way. But I've also found that it's not always my fault.

I recently decided to try some new (to me) styles, and ordered kits and bushings from a large supplier that is frequently mentioned on this site. I found that the sizes of the bushings were out by a few thousandths; from each other (they were supposed to be the same), from the measurements contained in the supplied instructions, and from the measurements of the actual components. Which raises the point: what tolerances do our suppliers adhere to?

I have seldom measured a pen component where I got the exact same result at multiple points; they are always close, but still different by a thou or two. Now some of that may be operator error on my part in using the calipers, but surely not all the time. So if the components aren't always perfectly true, then which measurement are we trying to reach with 100%perfection?

I now do much of my turning between centers (thanks johnnyCNC) and I'm confident that my results are pretty good; consistent measurements seem to bear that out. Yet, sometimes those barrels will end up with a seamless fit around 80% of the pen, but then have a slight imperfection at a single spot. If this was an out of round issue on my part I would expect a problem at two points on opposite sides of the pen. So, again, what measurements are we trying to match?

OK. Now that I have the preamble out of the way, here's what I do. I turn to within a couple thou of my measurements for the pen I'm working on; finish the barrel as appropriate for the material; assemble the pen; and then move on. I find that the fit is very good, and even in cases where I think that I would have liked to take another thousandth off, as was mentioned previously most people who don't know what to look for will not notice; they just see a beautiful pen.

I've only made a couple hundred pens so far, so I'm usually more eager to grab another blank to see what's waiting for me on the inside, than I am to fret about a nearly imperceptible mismatch on the sizings. If I ever come closer to the output of some of the masters here, I expect that my tolerances will become tighter, but I really hope that pens will always still contain elements of fun and discovery for me.

Also, one last comment. I'm not in any way impugning the efforts of those of you who strive for absolute exactness; as a matter of fact, I'm envious of that discipline, and that patience. Personally, however, I have just accepted a level of quality that I can consistently (mostly) attain with my current skills, and without inordinate amounts of angst. Hey, this is still supposed to be fun!