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Proportinal Dividers

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Project by GnarlyErik posted 03-16-2014 06:34 PM 1088 views 6 times favorited 7 comments Add to Favorites Watch

I needed a way to scale up a recent small project, so made these proportional dividers. The pictures are self-explanatory I think. These are simple and relatively easy to make using this simple method for layout. This method works for any sized dividers you may need – i.e., ratio or overall length.

My project needed to be scaled up by 25% (1.25:1), so the dividers are laid out for that ratio. But, since it is easy to do, I went ahead and made holes for 2:1 and 3:1 ratios too – just in case I ever need those in the future. To my eye, curves always look better than straight, so those are thrown in too. The one thing to remember is both end points and any ratio points in between should all be kept in line for the dividers to work accurately.

The detail photo shows all component parts, i.e., mahogany divider legs (mirrored), #8×24TPI x 3/4” brass plated decorative bolt, #8 nylon washer (used between the legs), #8 flat washer and #8×24TPI knurled nut.

(How to layout proportional dividers from scratch):http://lumberjocks.com/GnarlyErik/blog/40225

-- Candy is dandy and rum sure is fun, but wood working is the best high for me!





7 comments so far

View TopamaxSurvivor's profile

TopamaxSurvivor

15089 posts in 2428 days


#1 posted 03-16-2014 06:48 PM

Good idea and nice work. I probably would use a pantograph, but it can be a bit tedious for simple conversions.

-- "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View GnarlyErik's profile

GnarlyErik

209 posts in 887 days


#2 posted 03-16-2014 06:56 PM

Yep Topamax – I have a pantograph too, which is great for working with complicated drawings or shapes. But, sometimes it is much easier to just grab dividers to scale a few measurements up or down – especially for rectilinear shapes – no setup required! Also pantographs will not work when scaling from actual physical objects unless the object is very thin and flat.

-- Candy is dandy and rum sure is fun, but wood working is the best high for me!

View shipwright's profile

shipwright

5316 posts in 1551 days


#3 posted 03-17-2014 12:44 AM

Sounds like two foot-itis, scaling up 25% i mean.
Nice tool and handsome too Eric.
If I had one of those, I could make Friendship a 24 footer. :-)

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View johnhutchinson's profile

johnhutchinson

753 posts in 382 days


#4 posted 03-17-2014 01:50 AM

Beautiful craftsmanship !!! Seems that you’d want a wing nut to crank that sucker tight. And then maybe sandpaper where the two surfaces meet. But then it wouldn’t be art.

-- John - Central Ohio - "too much is never enough"

View GnarlyErik's profile

GnarlyErik

209 posts in 887 days


#5 posted 03-17-2014 02:46 AM

Well Paul, I suppose you could. We had a project at the shipyard once to ‘stretch’ a (F/G) crab boat by several feet. We did that by cutting hull near the center like finger joins, sliding the aft half back the required distance, sistering in the structural members and filling (and fairing) the skin in between. I was surprised at how well that worked!

So far as I know that boat is still fishing.

Actually John, with a nylon washer between the legs the brass knurled nut seems to work quite well. It can easily be tightened so you’d be in danger of breaking things if you forced, at least at this size (10”). Also, I remember seeing somewhere a sort of bent spring washer I thought I might try to find, but I don’t think that would be needed at all:

Cheers,
Erik

-- Candy is dandy and rum sure is fun, but wood working is the best high for me!

View shipwright's profile

shipwright

5316 posts in 1551 days


#6 posted 03-17-2014 03:04 AM

A copper nail and a rove will work too. Just the right tension.
If it gets loose a quick tap and it’s good to go again. I’ve used that on my pocket bevel for years

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View Rick's profile

Rick

7341 posts in 1785 days


#7 posted 03-17-2014 03:48 AM

ERIK:

Good story about that Boat! I would of Loved to have been Part of that!

AS LONG AS WE WENT FISHING AFTER!! OR! NO DEAL!! ...LOL..

Freakin Snow & Cold Weather Up Here in Canuck Land is Unbelievable!!

PS: NICE PROJECT!

-- How long is a Minute? That depends on which side of the Bathroom Door You're On!

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