Like your Kurt vise, I consider a boring head a foundational tool. As such, it has to work well, simply and reliably. Criterion DBL heads are actually quite basic with only a few moving parts but they are reliable workhorses that can last a hobby guy for a lifetime if not abused. Just to be clear, there are many other heads that are far better than a basic Criterion head - Wohlhaupter, Kaiser, Narex and others - but for most boring jobs, a DBL head will work just fine.
Buying a used head is economically the smartest route but you are right; buying used carries some risk. You will find that a head that has been abused or crashed will look it. If it looks like some bozo ran it into a work piece then reject it. Unscrupulous sellers will often not show the side of the head with the screws because they are invariably missing. If you can't see the screws, move on.
The body is simply black oxide coated that will fade with time and use. The tool holder part is satin chromed and stands up to wear a bit better. If it has no battle scars, the gib is totally intact and all the screws are there then take a good look. If it was used by a good operator, the head will have many years of use left in it and you can tell these heads because they will look like someone took good care of it.
All the DBL heads had removable shanks, with a 7/8-20 internal thread in back of the head. Adapters are available for almost every conceivable application, which is one reason why this head is in widespread use. If you see a good DBL head, know that you can remove the existing shank and adapt it to your machine.
In my opinion, a head that has been used is worth about 50% of its original value. Many sellers on ebay think otherwise and I have seen heads that have been beat to death selling for nearly $300. On the other hand, there are heads that are in fine shape that sell near the $120-140 range; those are what you're looking for. Be patient and it will come. What you're looking for is the description that says in "good condition". If you buy it and there is something wrong with it, ebay will back you when you ask to return it for a full refund so there is little risk. On the other hand, if you are well-heeled and wish for a new head, wait for a set to come up on ebay that has the head and a set of boring bars in a plastic case. They will usually run less than MSC charges for the head alone.
Some examples might help.
- Here is one in decent shape but you cannot see the screws. I would ask the seller to show them and the gib to me in pics. If they are all there and the gib is intact then I would make an offer. This head looks nearly new and I would offer $150 for it. He may counteroffer a bit higher but it won't be for the current asking price.
- This is a DBL-202 A model in very nice condition. It is clearly used but has been well cared for. No scars, the gib is intact and the gib screws are there and equal in height so the bearings are probably in there. It is listed as used so it must be fully functional or you can return it. I would have no problem offering $110 for this head and it would probably serve me for the rest of my hobby career.
As for bars, buy a decent set. Boring bars require very little sharpening. Borite bars only need an occasional touch up on the end and a light pass on the flat top. I use an extra-fine diamond stone for this.
If you want to economize on bars, buy a solid carbide Micro 100 bar with a positive lead when you find one for a good price. You will be pleasantly surprised at how well these bars cut and one with a 1.5" - 2" long shank will bore most holes in a hobby shop. Like Borite bars, these sharpen easily with a diamond stone and will last a lifetime if you don't crash it.
Good luck. If you need help with this, PM me.
