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Compass/Dividers
- Thread starter Aukai
- Start date
- Joined
- Dec 20, 2012
- Messages
- 9,422
The answer to this one depends on a lot of things. If you need accuracy then a height gauge and surface plate is useful. You can also use a cheap dial caliper to layout stuff. If ruler resolution is okay then a hermaphrodite caliper works. A square with a cobalt or carbide scribe will come in handy. Like I said, it depends.
- Joined
- Oct 4, 2016
- Messages
- 6,997
I would like to buy one, but it looks like it got more complicate than I thought. Carbide tip, so it will last, at this time I'm only looking for a simple tool that will last, but am open to suggestions for the best choice for a first one.
- Joined
- Jul 20, 2014
- Messages
- 1,386
I have Starrett odd leg dividers for scribing parts that are difficult for calipers or scribers. Mitutoyo makes carbide tipped scribing calipers with one longer jaw. Dividers are great for circles too. Or, you can use a surface gage or cheap General Tools© carbide tip scribe. If you do a lot manual lay out with blue dye, you can purchase what you need when you need it. What are you working on?
- Joined
- Sep 5, 2013
- Messages
- 3,203
I can appreciate you want to buy a good tool and not end up with a piece of junk, but dividers really are some of the very basic layout tools and I would not get too hung up on buying "the one and only best".
For starters, you rarely will need just one because they are suited to a particular size range. Yes you can scribe small arcs with large dividers, but they are awkward and will be frustrating. A small set works much better and has a finer feel in the hand for small work. It, of course, will not spread very wide though. Of the ones the photo below, the two on the left are my most used and feel nice for very small up to about 6" radius.
None of these have carbide tips (I don't even know if they make them with carbide tips) but are none the worse for it. If they get a bit blunted from use, hone them sharp again. Of interest may be that I have used these for many years and have yet to feel the need to sharpen them.
And as much as I really like the feel of a Starrett or Lufkin tool, none of these are. Three are Moore & Wright, and one is an SK brand. All were purchased used for no more than a few dollars each. I don't know if I would buy a tool like this without being able to hold it first. They're not complicated, but if there is even a slight bend in the screw the nut will bind up and be annoying. But then again, they're not (or shouldn't be) hugely expensive so if places like Ebay are your only option maybe that's a satisfactory risk. I've found all of these at second hand stores or local sales, and believe me my area is not strong on machinist tools.
As for new costs, I found new PEC brand for around $25.00 or the same size in new Starrett for four times that amount. Again, as much as I like a nice Starrett tool, there's no way I'd pay that much new. I just don't see it.
A couple of features to note: all three of the ones on the left of photo have solid nuts, solid in that they are not the "speed nut" or "quick adjust" nut that allows you to hold the legs together and rapidly slide the nut to adjust the spread. Starrett offers this feature and I have it on one of my smaller calipers. However I find it inconvenient and prefer the solid nut, but it could be just because I'm more used to the one way. The caliper on the far right is the "odd leg" or hermaphrodite caliper as well as being the "firm joint" style (without the spring and controlled adjusting mechanism). These are handy although require a bit of practise, and they're not usually expected to deliver high accuracy. Quickly scribing a line parallel to an edge for laying off fasteners though, they work fine. Adjusting the leg spread and tension on the nut can be an exercise in patience, but it gets there eventually. Not my choice if I can avoid it.
The big one across the top, well, just there to show how easy it is to make one if you need for a specific size. Two bits of wood, a bolt, and two nails for points. Can be changed to a compass by substituting a pencil on one of the legs instead of a point. I have five-foot ones at work for laying out geometric flower beds, paver paths, etc.
So maybe that helps to make a more informed decision. If you go looking for them in a tool catalogue they may be more likely found in the hand tool category rather than metrology. At least that's where they were in the catalogue I looked at. Good luck, and happy scribing!
-frank
For starters, you rarely will need just one because they are suited to a particular size range. Yes you can scribe small arcs with large dividers, but they are awkward and will be frustrating. A small set works much better and has a finer feel in the hand for small work. It, of course, will not spread very wide though. Of the ones the photo below, the two on the left are my most used and feel nice for very small up to about 6" radius.
None of these have carbide tips (I don't even know if they make them with carbide tips) but are none the worse for it. If they get a bit blunted from use, hone them sharp again. Of interest may be that I have used these for many years and have yet to feel the need to sharpen them.
And as much as I really like the feel of a Starrett or Lufkin tool, none of these are. Three are Moore & Wright, and one is an SK brand. All were purchased used for no more than a few dollars each. I don't know if I would buy a tool like this without being able to hold it first. They're not complicated, but if there is even a slight bend in the screw the nut will bind up and be annoying. But then again, they're not (or shouldn't be) hugely expensive so if places like Ebay are your only option maybe that's a satisfactory risk. I've found all of these at second hand stores or local sales, and believe me my area is not strong on machinist tools.
As for new costs, I found new PEC brand for around $25.00 or the same size in new Starrett for four times that amount. Again, as much as I like a nice Starrett tool, there's no way I'd pay that much new. I just don't see it.
A couple of features to note: all three of the ones on the left of photo have solid nuts, solid in that they are not the "speed nut" or "quick adjust" nut that allows you to hold the legs together and rapidly slide the nut to adjust the spread. Starrett offers this feature and I have it on one of my smaller calipers. However I find it inconvenient and prefer the solid nut, but it could be just because I'm more used to the one way. The caliper on the far right is the "odd leg" or hermaphrodite caliper as well as being the "firm joint" style (without the spring and controlled adjusting mechanism). These are handy although require a bit of practise, and they're not usually expected to deliver high accuracy. Quickly scribing a line parallel to an edge for laying off fasteners though, they work fine. Adjusting the leg spread and tension on the nut can be an exercise in patience, but it gets there eventually. Not my choice if I can avoid it.
The big one across the top, well, just there to show how easy it is to make one if you need for a specific size. Two bits of wood, a bolt, and two nails for points. Can be changed to a compass by substituting a pencil on one of the legs instead of a point. I have five-foot ones at work for laying out geometric flower beds, paver paths, etc.
So maybe that helps to make a more informed decision. If you go looking for them in a tool catalogue they may be more likely found in the hand tool category rather than metrology. At least that's where they were in the catalogue I looked at. Good luck, and happy scribing!
-frank
