What you need to know about forstner bits

hi I'm James Hamilton from stumping ups woodworking journal and this is what you need to know about Forester beds most woodworkers start out using Spade or paddle bits to bore large holes in wood but before long they realize that the far better solution is a Forstner bit because Fortuner bits are designed to cut clean flat bottom holes whether it's at ninety degrees or at an angle or even overlapping holes or holes that hang off the edge of a workpiece these tasks come in handy as your woodworking projects become more advanced the problem is there's a lot of different types of Forester that's out there and the differences go beyond just what they look like so let's try to clear up some of the confusion the biggest difference is that you're likely to see an Forstner bits are found in the guide rim this outer part of the bit the rim is what severs the fibers around the holes perimeter it guides the bit at the beginning of the cut which prevents it from skipping and walking across the top of the material and it controls the accuracy and the repeatability of the hole size so this is a critical feature there are a lot of different rim designs but if you go into your local hardware store or Home Center you're likely to find three major types you have the Sawtooth rims continuous or knife edge rims and wavy rims now what's the difference sawtooth rims Forstner bits are also sometimes called Multi spur bits the teeth work much like the ones on your table saw blade they cut into the fibers around the perimeter of the hole while the main cutters shave the wood up from the bottom of the hole because only the points along the rims do the cutting there's less friction and therefore less heat builds up that means you can run these bits at slightly higher speed and theoretically make faster cuts the downside though of the Sawtooth rim is that it's less effective and guiding the bit into the cut you may think that it's that center point that does all the guiding but like I said that outer guide rim is critical and the Sawtooth style tends to bite into the surface of the wood less effectively at the start of the cut sometimes slightly skipping or shifting the bit to the side which can spoil the edge of the whole soft tooth rims are also often a poor choice when boring at an angle because those teeth ten - chatter on top of the work surface and they can result in some rough cuts they also produce a rougher cut when the bit isn't fully engaged in the wood such as when you're overlapping holes or you're cutting a hole that hangs off the edge of your workpiece continuous rim bits get their name from their solid knife like rims these solves some of the problems that those sawtooth rim bits suffer from they score the fibers around the perimeter of the hole which creates a cleaner cut with less tendency to skip or walk across the surface of the work piece especially when you're boring at an angle or when the bit isn't fully engaged within the wood the downside is that all of that rim is in constant contact with the wood so it builds up more heat and heat those bits so you have to be careful at what speed you run continuous rim bits and you have to pay attention to your feed rate or you're gonna find they get dull fast wavery rim bits are designed as a compromise between sawtooth and continuous rim bits wavery rims do have points but they're more comparable to knife edges than sawed teeth the unique wavy grind breaks up the shavings more so they can be ejected easier and that keeps the hole cleaner and the bit cooler there's also less of the rim doing the actual cutting as compared to the continuous rim bits which further reduces heat buildup yet the rim is still effective in guiding the bit cleanly into the cut whether it enters at 90 degrees or at an angle or overhanging the edge of the work piece so those are the most common types of Forstner bits you're likely to encounter which should you buy well when a Forstner bit isn't new all three styles are generally going to make a clean cut but as you start to use them more one of them seems to perform much better in my opinion I gravitate towards the wavy rim bits they cut cleanly like a continuous rim bit but they stay cooler like a sawtooth rim bit and unlike the sawtooth bits they perform well in those instances where you may have to cut it in angle or make overlapping cuts such as when mortise several manufacturers are making wavy rimmed bits now but quality matters as much as design so don't just go out and buy the cheapest ones you can find cheap bits are poorly sharpened they wear out quickly the holes will be inconsistent in size and cut quality there are some tools that you can compromise on I'm not against buying inexpensive tools when they're the right ones but drill bits and horsin or bits should always be the best quality you can afford I own bits from several manufacturers but my favorite are the fish bits they are the only company that I know of that still Forge their bit in the old-fashioned ways they've been doing it in Austria since 1946 and forging produces a higher quality of Steel so the bits last two or three times as long as the cast steel bits that others are making I know people are going to say well fish is a sponsor so of course you're gonna say there's works the best so I performed my own tests to see if I could kill a fish bit so what I did is I took a chunk of a maple that's been sitting outside my shop for a few years and I started boring holes into the end grain which is much harder to cut than the long grain you typically work with I fed the bit fast and hard I didn't back it out to clear away the chips and help the bit to cool down I was really trying to overheat and dull the bit when I got done with one side I flipped it over and I started on the other side I remember this is maple end grain some really tough stuff i abused this bit in ways that are well beyond what the bid is going to go through in several years of regular use in your shop but after about a hundred of these holes I tested it again on some veneered plywood and it's still cut as clean and fast as when it was new so this might not be a scientific test but it made me a believer I do admit that the full sets of the fish bits are a little pricey but maybe you don't need to get the full set at once I'll put a link to them in the notes below this video just check them out and if you want to get like a half inch and a 3/4 maybe a 1 inch just the bits you're going to use most often and then the rest you can pick up as you need them for projects in the future at least that's what I do but whatever brand you go with I hope this little lesson in the types of bits helps you bore cleaner holes in your shop be sure to check out the latest issue of stumpy nubs woodworking journal it's always full of great woodworking tips tricks and tutorials designed to make you a better woodworker you can read and subscribe for free at Stephie Tubbs calm happy boring

Channel: Stumpy Nubs

Views: 530,078

Rating: 4.9301877 out of 5

Keywords: woodworking, stumpy nubs, fisch wave cutters, fisch drill bits, diablo, CMT, Freud, mortising, holes

Id: LeBFcCTXZkA

Length: 7min 2sec (422 seconds)

Published: Mon Sep 18 2017