I have a question about router speed and large bits. I want to try my hand at some raised panels. I have the 2 1/4 hp variable speed Bosch router (and table) and a 3 1/2″ raised panel bit. How fast should I be spinning this bit? Do I need to go as slow as the router will go or somewhere around the mid speed?
Is there any other advice out there for a begining panel maker? I mainly do remodeling but I would like to improve my woodworking skills.
Thanks
Replies
MSA1 ,
Check the bit or cutter specs from the distributor or factory , they may have guidelines for speed . Many Shapers spin 10 - 12 thousand rpm and routers may turn 20 thousand rpm . It seems router bits are designed to run at high speeds to produce the best cut . I would probably be inclined to take a few small passes at high normal speed .
dusty
I raise quite a few panels on routers. You are removing a lot of material, so taking it off incremental amounts is safer, results in a better finish and less stress on the equipment. You can raise the bit and/or move the fence as you go. I haven't seen a bit manufacturer that will specify a speed, only some say, not to exceed 25,000 RPM or some other figure. My fastest router is 27,000 RPM. Machines aren't much different in operations than a hand tool. You have to judge the speed of the bit and the speed at which you feed, based on the lumber and the ability of the machine and bit. If you push too hard or cut too deep, the sound of the motor straining and the feel of the wood snapping will be evident. Too slow a feed, and you dull the bit prematurely and often cause burning.
My horizontal raising bits measure about 3 1/4" overall. I normally run them in a big PC 3hp at 21,000 RPM. I often use a stock feeder and it is running around 12-15 feet per minute. In hardwood like oak, I may make 4-5 passes to get to full depth. The stock feeder is steady and consistent, which is what you want to be by hand.
I've tried out all the speeds available on my PC with different bits and wood. The router will slow down to 10,000 RPM, these are no load speeds. At the lower speeds, there is more of a tendency for the board to want to kick back and the bit to chunk. I can stall the bit quite easily at low speeds. For the combination of, my bits, lumber and methods, I get a nice finish without extra hand work at my routers top, no load speed of 21,000 RPM.
You may already know to do the end grain on one end first and work your way counter clockwise around the panel. If there is tear out on the end grain, the next cut down the side will eliminate it. I take a similar approach on the rails and stiles. If you do the copes first, you can use a backer block for tear out. When you cut the beads later, it will eliminate any hair that was left on the cope.
One other important issue is the hole in your fence and alignment with the bit bearing. I have a series of shop made fences for different bits. I use a combination of boring a suitable hole and raising the bit to get as close to a zero tolerance space around the bit as possible. This is a big help with short cross grain pieces. On the last depth setting of the bit, I try to get the fence in line with the bearing so that a straight edge will just kiss the bearing when held and slid back and forth on the face of the fence.
Beat it to fit / Paint it to match
I guess slow is not as slow as I thought. Thanks for the advice. I hope to get a chance to try some test pieces this week.
Hammer, thanks for the extra advice. I figured at least three passes as that is alot of material.
MSA1,
I have attached a chart of fouter bit speeds for you to see. It is in giant print because it is meant to be posted on the wall near your router, so you never have to think about speds again! I have mine posted in clear view near my router table.
The chart is taken from The Portable Router Book by Richard J. de Cristoforo.
Thanks for the chart, it will come in handy. Thats kind of what I was looking for.
Check out Oldham-USA.com. Click on router projects. Download and print rhe tutorial. Buy or build a coping sled and use it with a piece of scrap as a backing piece to eliminate tear out. Use featherboards to hold the workpiece down when using the coping sled. I also use the featherboard flat on the table when making the longer stile cuts.
For that diamater of bit you want your router running as slow as possible; 12,000 in the case of my own set up... My main worry is for the rated power of your router, I think it might struggle unless you use a combination of fense settings and height adjustments to keep the stock removal per pass to a sensable minimum; trying to hog off material quickly with a bit this size will cause things to go pear-shaped in a hurry, putting your stock and your router at risk, not to mention your personal safety...
Mike Wallace
Stay safe....Have fun
"Fense settings"? is this a typo or a term i'm not familiar with? I agree that 3.5" is alot of bit to be spinning and had already planned on making multiple passes. I hope 2.25 hp will handle it.
Fense shoulda read fence... irrespective of spelling, use of the fence is essential during the first few passes (in my own set-up at any rate). There's a limit to how far I can lower the bit before its dangerously close to the base of the router, leaving the bit far too high for the first pass.
I advance the fence to limit the amount of material to within the limits of the cutter and the router, gradually retracting the fence to a point where its flush with the guide bearing. Then and only them will I raise the cutter into the work in subsequent passes...Mike Wallace
Stay safe....Have fun
Good call on the power. I ran a test piece of poplar today and it took about 7 passes. :( It will work unless I get a huge wainscoting job or a full kitchen of custom cabinets (not likely yet). I think I will try to use the fence as you suggested to limit the cut per pass.
glad to be of help...Mike Wallace
Stay safe....Have fun
I find that a larger diam bit is more prone to having vibrations from imbalancce - or maybe if it is mounted in a router with even the slightest wear on the armature, it amplifies that vibration and you end up with chatter marks. I turn the router speed down slow and take only an eigth inch per pass, more or less.
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I didnt have a vibration problem but my 2.25 hp router is not in love with that big bit. It took about 7 passes (in poplar) to make one panel. 1/8" is about the best I could do.
How big is your router? How does it handle oak?
"I didnt have a vibration problem but my 2.25 hp router is not in love with that big bit. It took about 7 passes (in poplar) to make one panel. 1/8" is about the best I could do. ..."
I had the same router in my table for many years and had no problem raising panels in red oak in three major passes plus one clean-up (very light) pass. I've since upgraded to a 3.25hp router in my table and use my three 1617EVS routers for hand-held operations.
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How in the world did you accomplish a raised panel in three passes with a 1617evs? How fast were you going?
I ran some red oak today and it took another 7 passes, slow ones at that.
are you adjusting the depth of the cut or the elevation of the bit?
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I tried it both ways. For my first test piece I used the elevation and the second time (in oak) I tried using a fully raised bit and kept adjusting the fence. I think I liked the fence method better.
I'm not sure which one was more effective since I first used poplar then oak.
Sharp bit, slow to moderate feed rate, 8000rpm speed setting. I set the fence flush to the bearing and use the elevation adjustment to ease the bit into the wood.
Keep in mind that the 'horsepower' rating has little to do with the 'actual' power of the machine.
For instance, the 3.25hp router is rated at 15amps; simple basic calculations show the hp to be 2.4 (15A x 120V = 1800W; divide the Watts by 746 to get 2.4hp; then apply an efficiency factor of 85% and you get about 2hp)
Using the same calculations for the 2.25hp router, which is rated at 12A yields the following: 12A x 120V = 1440W; divide 1440W by 746 to get 1.9hp; the efficiency factor brings the result to 1.6hp.
Bottom line is that while there is a difference in power between a 2.25hp and 3.25hp router, it's not as dramitic as the advertised ratings lead one to believe.
The main difference between my 2.25hp and 3.25hp machines has been feed rate. I can feed material faster through the 3.25 because it doesn't strain as much.
Regards,
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Just curious Bill... how thick a panel are you raising...??? Do you use a flush back panel or back cut to get the side tennons to the required thickness..??Mike Wallace
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"Just curious Bill... how thick a panel are you raising...??? Do you use a flush back panel or back cut to get the side tennons to the required thickness..??"
Panel thickness is 3/4". The last panels I did were cove profile on front deep enough to flush to the rails and stiles, then I undercut the backside.
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ahhhhh..... that explains it some... I normally raise much thicker panels, without the undercut...
whatever works ehh..??Mike Wallace
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Panels thicker than 3/4"??? Why?
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interesting burr elm... I was lucky to get the panel edges to cut sections through quite a few of em... PITA to finish (wax) but well worth the patience...Mike Wallace
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Mine isa three horsed variable speed. I rarely work oak and don't remember taking a bigger bit to it.
I have a Williams and Hussey Molder that I use for heavy work.
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I would turn the machine on slow at first and run it until it doesn't viabrate. As soon as the table starts to viabrate back it off a fraction.
Also, use a brake through fence [ mdf] so the cutter is the only part showing. Alot safer and prevents panal edge getting stuck on the fence beyond the cutter.
To install, clamp a 10mm fence to your [operator side] existing fence. Holding the fence out clear of the cutter, start the machine and gently return on to the cutter until it runs free. Turn off and clamp fence at other end.
Hope that makes sense.
Roo
I was thinking about raising the speed a bit. As far as the break through fence, I have the Bosch table with the split fence. I havent had any problems with the panel getting stuck on the other side.
What it does is prevents you having to have a large gap between the fences. For narrow panals esential.
Now I know what you mean. When I was cutting my test piece (just a 1x6) I did have a little problem with the ends.
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