OK, I have this 1-1/2″ Forstner bit I’ve been using in soft wood. Been using it at medium speed in my 3-speed drill press, because there are no instructions. It’s a new CMT bit, and the instructions that are with it are for their router bits (OK, so I’m not supposed to use it above 22,000 rpm LOL!). Would like to use it at the highest safe speed, though, which in my drill press probably isn’t all that high.
These companies are funny sometimes. I took out the instructions for my Incra 1000 the other day to check on something, and realized that one of the pictures they featured shows the gauge going toward the wrong edge of the saw blade — i.e., from the back toward the front. LOL.
forestgirl — you can take the girl out of the forest, but you can’t take the forest out of the girl 😉
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Speeds and feeds - a critical element in machining, woodworking, metal working, etc. There are a variety of Forstner bits out there - the one's with teeth can take higher speeds/faster feeds while the more traditional Forstner bits with a beveled cutting edge need to go slow for both speed and feed. Most of mine are the latter and I run them at the low speed range on my drill press - usually between 400 or 500 rpm. And I feed them slowly, retracting the bit frequently to clear the hole of chips. I do this regardless of wood - hard or soft in part because I want to avoid having to sharpen them unless I absolutely have to. If I was doing a production operation and wanted to reduce process time, I would get a good, commercial Forstner bit - they are more expensive than the usual ones featured in the woodworking catalogues. Here's another place where a good industrial supplier can set you up with the correct tooling.
Hi Ed (or is it Gregg?) -- the CMT is a saw-tooth design. Even with this design, I tend to lift-and-clear also. Have never been on to force the issue much with cutting tools :) We'll see what Steve's chart has to say after he gets home I guess.
So far the level I'm working at isn't demanding serious efficiency, but I'll keep the industrial idea in mind if I come up with a hot design.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Ask and you shall recieve:
1/4 - 3/8 = 700 RPM
1/2 - 5/8 = 500 RPM
3/4 - 1 = 500 RPM
1-1/8 - 1 1/4 = 250 RPM
1-3/8 and above = 250 RPM or less.
So pretty much the scenario is go slow go slow go slow and you never know if you're going slow enough until something feels wrong...
Steve - in Northern California
My goodness, where are my manners? I neglected to thank you for the speed chart. Will print it out and put it in my very fat woodworking notebook!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Ummm...sorta, they're pretty conservative.
Best speed also changes with the tooth style, depth, and especially the relief. Your obvious problem is heat, and less builds up with 1/4" depth than 3". Also a big difference between softwoods and hardwoods; and even within: go slower in southern yellow pine (much) than northern pine.
In another view, as you increase the speed you can also increase the feed rate, but only up to a point. You want to stay below that point. IOW, if you can bore the hole with 500rpm at one rate, or at 1000rpm at double the boring rate, you've got the same heat generated. Keep going and you become less able to clear the waste fast enough, the boring rate slows, the heat gets trapped, and the temp goes up fast.
So, keep the bit clean on the outside.
Yes, I do use Pam on the BS; yes I do finishing; yes, the Pam does have a noticable effect; no, the relatively tiny amount does not effect the finishing.
No, I do not use Pam on drill bits; nor any other lub when drilling wood.
Gerry
Yes you are correct, they are very conservative but not knowing the quality or the speed range that was actually available I decided to error on the safe side. These were the low end speed ratings of a set that I bought from WoodCraft. Runnout and vibration are a couple of other factors that are often overlooked. Both will cause you problems which are lessend with the lower speeds.
Steve - in Northern California
Jamie, I have a chart with speed ratings for Forstner Bits for sizes 1/4 to 2 1/2. It came with a set I bought at WoodCraft a couple of months ago. So far it appears pretty accurate. The set I bought ran about $90.00 so they are not industrial grade by any means. The do work pretty well and suprisingly they don't burn when I push them hard.
Unfortunately, the chart is hanging on the wall next to my drill press so you'll have to wait until I get home tonight.
Steve - in Northern California
Hi Dave. Here's a question for ya: I read somewhere (might have been the Timberwolf/Suffolk Machinery site) that PAM (cooking spray) is a good lubricant for bandsaw blades. Do you think that would work for bits too? It's really cheap when I buy it at Costco 3 cans at a time!
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Both Dave and Steve are giving you good info - essentially run Forstners at a low speed (well below 1000 rpm) and feed sufficiently to cut the wood without burning the bit.
But lubricants are another issue. In metal work they are a must. But in woodworking, they are really a problem. You'll never get the real scoop on what's in a lubricant (including PAM) that could cause serious problems with finishing down stream. Additionally, woodworking machines have enough problems with pitch build-up without adding a lubricant - you'll end up steam cleaning or using strong solvents constantly to keep your machines in good order. The real key is matching the tooling with what you are cutting - and they may mean several different kinds of blades/tooth patterns. If you are cutting good cherry boards and then running MDF through the same machine, you're not going to get the same results. Don't spend money on lubricants (except for the machine parts themselves) - invest in good cutting tools and whatever it takes to keep your machines clean and free of buid-up.
I'm not all that sure your hypothesis is correct. But then again I am not all that certain of what your limits are vis a vis lubricants.
In a most of the sawmills I have been through, they are using a oil/water mixture for most of the bandmills especially the headrig. If they are using thin kerf splined arbor saws for resawing, the guides on those saws require a water/oil mixture (pumped through the guides).
I worked with Bernie Sandaro when he was developing Dri-Coat etc and was trying to make inroads into primary mills. Unfortunately, most of the very postive result he was getting were ancecdotal. I recommended he do a comparative study with controls but he was an entrepreneurial inventor and didn't appear to be interested in the nitty-gritty specifics. The filers I talked with felt the blades stayed sharper longer and did not get as much pitch build-up.
Obviously you cannot use water/oil mixtures on dry wood. I have found that most individuals overuse products like Dri-coat. It scares me when individuals use silicon lubicants on blades but I guess that the finisher in me. I like to keep my tooling sharp and clean, especially the hook side of the cutting edge.
I definitely use lubricants (paraffin wax) on the surfaces of my stationary machines (Table saw, jointer, shaper) and on the bottoms of my hand planes. This provides a very definite reduction in friction such that I don't have to work so hard and can concentrate on guiding the pieces through.
When I speak of lubricants for woodworking machines, I'm referring to cabinet shops - both professional and hobbyist - as you pointed out, dry wood (mc approx. 7%) should not be milled/machined with lubricants. I have been in a number of furniture manufacturers running all types of milling/shaping operations all done dry.
The half dozen sawmills I have visited (a split of band and traditional saw blades) also were not using lubricants and they were cutting all species - from PA cherry to oak. However I do see the merits in using a lubricant - question is what to use that won't ultimately affect the wood even after kiln drying and milling.
I also use paraffin on my hand tools and on the machined surfaces of my stationery tools. However the original question was "is it OK to use PAM" to help in cutting wood on the bandsaw. And as we have both stated, on dry cabinet woods, no. And if your machine is a dedicated cabinet shop tool cutting only dry woods, then any lubricants are going to create a great mess.
http://www.lubielube.com/01_Pages/Lubricants.htm
Actually lubricants are used quite q bit in the woodworking industry. We use a lube on our 12" Wadkin moulder for the bed and also on our Timber Harvester Bandmill to cool and lubricate the blade.
What kind of wood processing are you doing? Is it architectural millwork? You also state using the lubes for a bandsaw operation - again what stage of the process and what's the end use? The firms I have visited are all high - very high end - furniture manufacturers using cherry, mahoganies and walnut among other species - all solid wood and usually at a 7/8% moisture content. These folks would be very reluctant to use a lube even on their high speed shapers for fear of impacting the wood itself and its finishing characteristics.
On the other hand if you are using woods with higher pitch/tar content like pine or spruce or fir and the end product is a milled moulding that will sit in a warehouse, then lubes might be a great way to preserve your cutting tools.
And again, the original question was is PAM OK as a lubricant in a home woodshop operation. And again I state no because we don't know the contents of PAM and even if it is neutral, home workshop machines are not designed for lubricants. The machines you mention are production units with dedicated tasks. Not so with home woodshop machines and I stand by my answer - lubricants don't have a place with home shop equipment.
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