Rhyolith
Established Member
In a lot of the threads about hand drills this pops up, so thought I would waffle about it a bit 
Spring Chuck - Probably the most common in hand drills, don't think I need to describe it. They seem especially prevalent amongst the English made drills; here is such an example from a Suffolk Iron Foundry hand drill.
SIF Spring Chuck by Rhyolith, on Flickr
I actually see no situation where the spring chuck is the best design, I only assume patent and/or cost issues prevented it from being completely replaced by the next design on this list.
Protected Spring Chuck - Essentially its an improvement on a standard spring chuck. Instead of the coiled springs there are these paper clip like things that are shielded inside little slots and hence hard to damage. I think North Bros invented or at least pioneered this design, passing it on to Stanley who used it in their 803 and Continental models to name a few. Millers Falls also using it in many of their drills, the example below is from a Millers Falls No.2
Wire Chuck by Rhyolith, on Flickr
For Hand Drills this is my favourite design as they are quick to do up and undo, as well as centring the bit reliably every time. I can see an argument for Jacobs being superior, however for me the convenience of not needed (and not loosing!) and chuck key wins out. This can be made very compact and able to take quite large bits for their size, in tight spaces in find this loss of a millimetre of radius relative to the maximum bit size is worth its weight in gold; the North Bros No.1530 is the best example of this.
Springless Chuck - Possibly the Most unusual offering here it seemed to be used exclusively by Millers Falls Co. in their smaller hand drills. As the name suggests it has no springs at all, with the jaws being guided inside slots and pins in order to remain in position. The jaws can only be retracted by gravity or pushing them back into the chuck with your finger.
Millers Falls No.3 Chuck by Rhyolith, on Flickr
I like the design and it works well on smaller hand drills, however the inconvenience of the jaws not self retracting and the fact they can only hold relatively small bits relatively to their size makes them inferior to the Protected Spring Chuck in my opinion.
Jacobs Chuck - Doubt this one needs any description.
No.36 Chuck by Rhyolith, on Flickr
The main advantage of these is superior grip to any other 3-jaw variant, however at the cost of having to use an annoying and loosable chuck key. I like these on big powerful drills such as pillar/bench drills and electric tools that generally don't leave the workshop, as the issue with the chuck key is less annoying then. I would defiantly prefer my union bench drill to have a Jacobs.
Union A1 2-Speed by Rhyolith, on Flickr
2- Jaw Chuck - This design is know by most as the type used in woodworking braces
Millers Falls No.87 Chuck by Rhyolith, on Flickr
I like the traditional 2-Jaw Chuck for chest drills, as with these more powerful tools the guaranteed lack of slippage is a major advantage.
Spring Chuck - Probably the most common in hand drills, don't think I need to describe it. They seem especially prevalent amongst the English made drills; here is such an example from a Suffolk Iron Foundry hand drill.
SIF Spring Chuck by Rhyolith, on FlickrI actually see no situation where the spring chuck is the best design, I only assume patent and/or cost issues prevented it from being completely replaced by the next design on this list.
Protected Spring Chuck - Essentially its an improvement on a standard spring chuck. Instead of the coiled springs there are these paper clip like things that are shielded inside little slots and hence hard to damage. I think North Bros invented or at least pioneered this design, passing it on to Stanley who used it in their 803 and Continental models to name a few. Millers Falls also using it in many of their drills, the example below is from a Millers Falls No.2
Wire Chuck by Rhyolith, on FlickrFor Hand Drills this is my favourite design as they are quick to do up and undo, as well as centring the bit reliably every time. I can see an argument for Jacobs being superior, however for me the convenience of not needed (and not loosing!) and chuck key wins out. This can be made very compact and able to take quite large bits for their size, in tight spaces in find this loss of a millimetre of radius relative to the maximum bit size is worth its weight in gold; the North Bros No.1530 is the best example of this.
Springless Chuck - Possibly the Most unusual offering here it seemed to be used exclusively by Millers Falls Co. in their smaller hand drills. As the name suggests it has no springs at all, with the jaws being guided inside slots and pins in order to remain in position. The jaws can only be retracted by gravity or pushing them back into the chuck with your finger.
Millers Falls No.3 Chuck by Rhyolith, on FlickrI like the design and it works well on smaller hand drills, however the inconvenience of the jaws not self retracting and the fact they can only hold relatively small bits relatively to their size makes them inferior to the Protected Spring Chuck in my opinion.
Jacobs Chuck - Doubt this one needs any description.
No.36 Chuck by Rhyolith, on FlickrThe main advantage of these is superior grip to any other 3-jaw variant, however at the cost of having to use an annoying and loosable chuck key. I like these on big powerful drills such as pillar/bench drills and electric tools that generally don't leave the workshop, as the issue with the chuck key is less annoying then. I would defiantly prefer my union bench drill to have a Jacobs.
Union A1 2-Speed by Rhyolith, on Flickr2- Jaw Chuck - This design is know by most as the type used in woodworking braces
Millers Falls No.87 Chuck by Rhyolith, on FlickrI like the traditional 2-Jaw Chuck for chest drills, as with these more powerful tools the guaranteed lack of slippage is a major advantage.
