Member
Sydney, Australia
Brush handle number 2, and a prime example of how one totally-not-my-fault machining problem can lead to a brush handle that's usable but quite unsatisfactory.
[Image: 30mEFJV.jpg]
First brush on the left, second on the right. Theory on far right.
So what happened was that the turning on the lathe went great, and milling the grooves in the top half also went great. What went wrong was that the very bottom of the ball-nose endmill I used for making the bottom grooves smeared the material in the very middle of the grooves. Tilted things to avoid that area of the endmill, but had to go deeper to compensate. Got the wrong angle and I ended up with an incomplete groove and had to readjust. All of this ate away at the overall diameter of the lower half until the chamfer was completely gone (and I ate into the ring just above that section). Fits nicely in the hand but the sharp corners aren't really comfortable.
On the up side, things that went right:
* Grooves on top half are much more durable. You can see how in the first version the thin edges were prone to being deformed.
* Surface finish is much better all over, nice and shiny now. Got better cutters to thank for that.
* Proportions are now much better, waist is thinner but longer and is much more comfortable to hold. I don't think I'm going to make any changes to the design unless they're for aesthetic reasons.
To do:
* Buy more delrin, I'm out.
* Work on my parting process, not entirely satisfied with how it's done at the moment.
* Make bottom section and a collar to fit, see how easy it is to insert/remove. The hole in this new version is 30 mm, so it should be able to take collars that hold knots up to 28 mm, and if I do a special 2 part collar 30 mm knots should also work, but that size knot is too big for my preferences.
[Image: 30mEFJV.jpg]
First brush on the left, second on the right. Theory on far right.
So what happened was that the turning on the lathe went great, and milling the grooves in the top half also went great. What went wrong was that the very bottom of the ball-nose endmill I used for making the bottom grooves smeared the material in the very middle of the grooves. Tilted things to avoid that area of the endmill, but had to go deeper to compensate. Got the wrong angle and I ended up with an incomplete groove and had to readjust. All of this ate away at the overall diameter of the lower half until the chamfer was completely gone (and I ate into the ring just above that section). Fits nicely in the hand but the sharp corners aren't really comfortable.
On the up side, things that went right:
* Grooves on top half are much more durable. You can see how in the first version the thin edges were prone to being deformed.
* Surface finish is much better all over, nice and shiny now. Got better cutters to thank for that.
* Proportions are now much better, waist is thinner but longer and is much more comfortable to hold. I don't think I'm going to make any changes to the design unless they're for aesthetic reasons.
To do:
* Buy more delrin, I'm out.
* Work on my parting process, not entirely satisfied with how it's done at the moment.
* Make bottom section and a collar to fit, see how easy it is to insert/remove. The hole in this new version is 30 mm, so it should be able to take collars that hold knots up to 28 mm, and if I do a special 2 part collar 30 mm knots should also work, but that size knot is too big for my preferences.
Posting Freak
Null I appreciate you sharing your design and creative process with us - we are so often in life presented with examples of great design, performance, literature and tend to believe that the genius responsible for them just had a bolt out of the blue and created perfection on the first try because they are unique geniuses. The reality is that yes, there is amazing creativity, but in almost every instance its a large dose of plain hard work and years of trial and error. If you've ever read any of Mark Twain's witticisms you are tempted to think the man just had a gift with words. Of course he did have a gift but if you've ever seen his notebooks every one of those quotable witticisms went through many, many revisions and to be honest, the earlier drafts weren't all that good. Thanks for letting us into your shop and sharing your thought processes.
Marko
Marko
Member
Sydney, Australia
Thanks all, it's always encouraging to know that other people are interested.
Cincinnatus , I'm using Autodesk Inventor. Free for students and educators, which is the main reason I chose it.
Cincinnatus , I'm using Autodesk Inventor. Free for students and educators, which is the main reason I chose it.
Member
Sydney, Australia
I think the design is settled. Three piece design, it seems that regardless of how careful I am water always gets inside the recess for the collar so I might as well make it easy to dry or clean if needed. Better than having a blind hole or needing to clean a female thread like the first design back on page 1. Handle is perfect for me, base sits nicely in my palm, middle finger is comfortable in the waist and the top section is long enough that I don't get lather on my fingers unless it's truly overflowing.
Knots shown are a 20 mm Ace Shaving silvertip and a 20 mm WD synthetic. The collar for the silvertip looks funny since I had to make a larger collar for it, so you're actually seeing the original smaller collar epoxied into a larger one. While we're on the subject, I think the handle demands a bigger knot, 20 mm looks a little sad (especially the synthetic).
Swapping out knots is reasonably easy if you've got dry hands, the part with the bolt has some pattening in it so that you can just press it into your palm and twist.
[Image: UNembOp.jpg]
[Image: fYlAD6ul.jpg]
[Image: NdjnYgNl.jpg]
[Image: YWecuKdl.jpg]
Now all that's done I just need to decide on a nicer looking material than black delrin, while the modular design is nice it's just not worth it for such a cheap material. First thought was mokume gane but at four figures for a suitably sized piece that's out of the question! Should make a stand, too.
Out of curiosity, I showed it to a friend and he said the quality was good enough for me to sell them. Given the styling I'm not too sure of the market size, but would anyone actually be interested in a non-modular version of this design, or a shorter one where I basically chop off most of the bottom section to leave just a flared base?
Knots shown are a 20 mm Ace Shaving silvertip and a 20 mm WD synthetic. The collar for the silvertip looks funny since I had to make a larger collar for it, so you're actually seeing the original smaller collar epoxied into a larger one. While we're on the subject, I think the handle demands a bigger knot, 20 mm looks a little sad (especially the synthetic).
Swapping out knots is reasonably easy if you've got dry hands, the part with the bolt has some pattening in it so that you can just press it into your palm and twist.
[Image: UNembOp.jpg]
[Image: fYlAD6ul.jpg]
[Image: NdjnYgNl.jpg]
[Image: YWecuKdl.jpg]
Now all that's done I just need to decide on a nicer looking material than black delrin, while the modular design is nice it's just not worth it for such a cheap material. First thought was mokume gane but at four figures for a suitably sized piece that's out of the question! Should make a stand, too.
Out of curiosity, I showed it to a friend and he said the quality was good enough for me to sell them. Given the styling I'm not too sure of the market size, but would anyone actually be interested in a non-modular version of this design, or a shorter one where I basically chop off most of the bottom section to leave just a flared base?
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