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  1. #11
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    Quote Originally Posted by tonyfoale View Post
    Many thanks. I have identifird it as a Sears Roebuck 149.21871. It is a couple of decades younger than I thought at 1970s/early 80s. Anyway I couldn't find anything on that site to answer my question. Actually my question isn't really machine specific, cutting surface speeds depend on material to be cut and maybe material of the blades. In the absence of additional information I'll aim for around 12,000 rpm which should give conservative cutting speeds. If the bearings/bushes wear out I'll modify it to take ball bearings.

    Do not try to run the cutterhead at 12,000 RPM! you are going to want about 7,000 RPM max with a machine with bushings rather than roller bearings. those high speeds will just tear up the machine You probably want to double your motor speed, In the States it would be 3450 RPM @ 60hz. in Europe running @ 50hz. will run a tad slower
    From the time you're born till' you ride in a hearse, there's nothing so bad it couldn't be worse!

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  3. #12
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    Quote Originally Posted by Al8236 View Post
    Do not try to run the cutterhead at 12,000 RPM! you are going to want about 7,000 RPM max with a machine with bushings rather than roller bearings. those high speeds will just tear up the machine You probably want to double your motor speed, In the States it would be 3450 RPM @ 60hz. in Europe running @ 50hz. will run a tad slower
    i have a Hitachi powered hand plane which states 14,000 rpm and which I measured to be 12,900 rpm unloaded. It has an OD across the blades of 64 mm. The Sears/Craftsman is 54 mm. So the surface speed of that at 12,000 rpm will be 72% of the manual plane. That being the case I am unsure as to why you warn against that speed. As I mentioned, if the bushes are not up to the job I can easily convert to ball bearings unless there is something that I'm missing. The limit as far as I can see is heating of the blades.
    Is there any reason that eludes me that lets a manual machine spin around double that of a fixed machine?

  4. #13

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    Planer Jointer

    Quote Originally Posted by tonyfoale View Post
    I have a small and very old cast iron Craftsman planer which I bought at a yard sale when I lived in the US. Other than a "don't cut you fingers off" notice there is no other info with it. The table is 4 or 5 inches wide and the drum is a touch over 2" diameter with 3 blades. The spindle looks as it it runs in plain bearings but I have not dismantled it yet.
    Does anyone know what RPM the spindle should spin at? Failing that, can anyone give me a guide to surface cutting speeds for wood, Google came up with a lot of useless info, many planer users seem to be confused between cutting speed and cutting feed.
    I have a jointer similar to what you describe. I found a manual on Vintage Machinery.org Website. It lists the age as in the 1930 era, with the cutter speed at 4400 rpm. Hope this helps.

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  6. #14
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    I just went out to the shop and looked at my power hand plane and my craftsman jointer the hand plane runs at 12,000 RPM with about a 2 to 1 reduction to the cutter head and the jointer runs a 3450 RPM motor with a 2 to 1 Increase to the cutterhead. that is what I am going by. Do what you will but I don't think the jointer was ever intended to operate at those speeds.
    From the time you're born till' you ride in a hearse, there's nothing so bad it couldn't be worse!

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  8. #15
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    Here is the Parts list and exploded view of the 149.21871 from Parts Direct.

    Help needed, Craftsman wood planer.-14921871-jointerplaner.png

    If it is that model then it appears to have Ball Bearings (2x item 4) and has a 4" drive pulley. I would think the bearing might hold up for a few minutes at that speed but IMHO 12k rpm seems a bit fast for a jointer. Even with a 3450 motor the pulleys around a 6" & 2" to reach ~10K. Personally I would shoot for around 8K Max. Cutter head speeds on larger units (6") is around 8k for a 1.88" head (Grizzly Page7).

    Hand held Planers are a different beast and used differently. A Jointer is generally used on wood for taking the crown or bow out of it and reduced sanding for finish. I'm not sure tool SFPM is generally used with Jointers because the "Hand" feed rate of the material is pretty slow so as to get a good finish and the cuts are usually < .0625. Blades are typically some type of HS tool steel. My guess would be W1 or similar to handle the durability issue with a lower HRC. My old "American" (early 70's Taiwanese) WJ-6 (6") will take a piece of 6" Walnut and make it baby butt smooth in 2-3 passes but it has a 1.5hp motor.

    PJ
    Last edited by PJs; 03-10-2018 at 11:05 AM. Reason: jointer use
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  10. #16
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    Quote Originally Posted by Al8236 View Post
    I just went out to the shop and looked at my power hand plane and my craftsman jointer the hand plane runs at 12,000 RPM with about a 2 to 1 reduction to the cutter head
    So 6,000 rpm at the cutter, I measured the speed on my hand version and it was the cutter head that spun at 12,900. Strange that there is such a difference.

    Quote Originally Posted by Al8236 View Post
    I don't think the jointer was ever intended to operate at those speeds.
    I am sure it wasn't.

    So what are the pros and cons of running fast and slow?
    I can see that for a given feed rate (manual in this case) the fast cutter would need to make a smaller cut which would reduce the blade load but on the other hand the blade would heat more due to the speed. The power requirement would probably be higher but that is of little concern to me because I'll just put a suitable motor on it, but of course it would be of concern to a manufacturer because it would increase cost.
    What about finish, does a fast moving blade give a smoother cut?

    I seem to have opened a can of worms with my inquiry, but I don't like to just accept things in ignorance. I need to know why.

  11. #17
    [email protected]tonyfoale.com tonyfoale's Avatar
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    Quote Originally Posted by PJs View Post
    If it is that model then it appears to have Ball Bearings (2x item 4) and has a 4" drive pulley. I would think the bearing might hold up for a few minutes at that speed
    Yes it has ball bearings and they would have no problem taking that speed. My only mechanical concern with the speed would be balance of the drum, although that isn't a problem with my manual machine. A problem could be with the stock size and type of V drive belt, one would need to run small pulleys to reduce belt throw out but stock V belts are not great with small pulleys. I will use a small poly-V belt which would handle the speed and torque with ease.

    So I have no mechanical concerns about running at high speed, the question is still "what is the best speed to use?" and I am no further down that road.

    Many thanks for taking the time to dig out the sketch. In fact thanks to everyone who has replied.

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    The first 3 small jointers in the grizzly catalogue are as fellows
    1 7/8" 2 knife cutter head 10,000 rpm
    1 7/8" spiral head (inserts) 8,000 rpm
    2 1/2" 3 knife cutter head 5,000 rpm
    My personal approach would be a tad slower than faster, less chance of burning the knives with a slow feed rate. At times a slow feed rate is most desirable with tear-out prone or wild grain wood, especially with straight knives.
    On a side note, and this may start a row, but I have got the best results from my 6 inch jointer by jointing the knives by hand. (Jointing knives is running a sharpening stone along them with the head spinning, commercial industrial machines such as molders have a built in means of doing this, not only can the knives be sharpened during a production run with out stopping the machine but the knives are cutting all equaly ) many may say it is to unsafe but using the out feed table to guide the stone seemes to be safe enough and the results good enough that I will do it. The results are good enough that I am planning on making a setup to hold a stone with mabey linear bearings for my planer. Don't mean to start any thing but the results have been impressive getting all the blades cutting dead equally.
    Hope some of this helps.
    Eric

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  14. #19
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    So I have no mechanical concerns about running at high speed, the question is still "what is the best speed to use?" and I am no further down that road.
    In Post #3 hemmjo (John), in speaking about a "planer" (US) with auto feed rates that have "recommended" feed rates and that the types of wood, grain structure, moisture content, sappiness etc. will all play a role in "Feed rate" based on head size. I see this no different than mill or lathe working metal working but these still have multiple subtle parameters that need accounting for, like tool geometry, rake angles, sharpness, rigidity, etc, etc. There are formulas for sure, based on material of Known "types" grain, hardness etc., but they are still guidelines in effect and tend toward User experience on the whole as to how to perform a certain operation.

    I tried to have a further look for recommended optimum speed info on wood working and wasn't able to find much either. There was/is some information on blade speed/SFPM for wood bandsaws but other than that it seems to be black art or guess and bi-golly. The manufacturers must have some info or empirically determined this info long ago...like metal machining and it's being brought forward.

    "Jointers" (US), especially home shop types are typically single speed with hand feed. This tells me that if we look at what is out there for "Speed/SFPM" for these type tools, it should be a guideline or Starting point as many here have stated. If someone wants to try something else "Out of the Box" to learn or other intended purpose, that may be worth pursuing. My issue is always about safety, and a ~1 pound drum with 3 semi-exposed blades held in with set screws, spinning at 12K with marginal bearings in a 60-70 year old casting "Feels" a bit riskier than I would be willing to experiment with. All be it not much different than laying a knee on the pavement at 2+G's at 120+ mph in a corner. However a good builder would always magniflux the crank of a 12K machine prior to getting on the machine himself...nothing like a hand grenade at 120+.

    The only other suggestion I have would be to chat with Brendon here on HMT if he is still around or on his website. He is one of those who's little finger Forgot more than most know about wood working.

    PJ
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  16. #20
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    Quote Originally Posted by PJs View Post
    In Post #3 hemmjo (John), in speaking about a "planer" (US) with auto feed rates that have "recommended" feed rates and that the types of wood, grain structure, moisture content, sappiness etc. will all play a role in "Feed rate" based on head size.
    The info that I found seemed more concerned with feedrate and scallops per inch and then sfm only insofar as it affected the scallops per inch.

    Quote Originally Posted by PJs View Post
    I see this no different than mill or lathe working metal working but these still have multiple subtle parameters that need accounting for, like tool geometry, rake angles, sharpness, rigidity, etc, etc.
    With metal we have fairly well defined limits for efficient tool speeds. Too slow and generally you blunt the edges too quickly, too fast and heat becomes a problem. I was expecting/hoplng that limits for wood would be just as easily available but it seems like the wood community is less concerned with sfm. In a commercial environment the same principal consideration for metal and wood must be production rate. The faster your sfm the faster can be the feed and higher the production rate. I would be very surprised if the wood cutting industry wasn't just as interested in this as the metal cutting world.

    Quote Originally Posted by PJs View Post
    I tried to have a further look for recommended optimum speed info on wood working and wasn't able to find much either.
    That's why I asked here.

    Quote Originally Posted by PJs View Post
    "Jointers" (US), especially home shop types are typically single speed with hand feed. This tells me that if we look at what is out there for "Speed/SFPM" for these type tools, it should be a guideline or Starting point as many here have stated.
    It was the search for a starting point that led me to measure the speed on my hand held planer. That was 12,900 rpm with cutters at an 18% greater diameter than the Craftsman. At 12,000 rpm the sfm would only be 78% of the hand plane which is why I thought it to be conservative. Actually the label on the plane says 14,000 rpm but that would have been on UK electricity, the voltage here in Spain is a little less which is probably why I measured 12,900. I know that other hand planes spin at around half of this but I think that this is probably due to motor power. My Hitachi has a 700 watt motor.
    I find it hard to accept that the sfm of a fixed machine has to be around 1/2 that of a manual machine.

    Quote Originally Posted by PJs View Post
    If someone wants to try something else "Out of the Box" to learn or other intended purpose, that may be worth pursuing. My issue is always about safety, and a ~1 pound drum with 3 semi-exposed blades held in with set screws, spinning at 12K with marginal bearings in a 60-70 year old casting "Feels" a bit riskier than I would be willing to experiment with.
    I am probably somewhat less risk adverse than the average but I have no wish to get hurt either. Regarding your specific points; I don't know why you regard the bearings as marginal. Bearings of that size are rated for much higher rpm and the loads are well within limits. Actually the casting is much younger than your estimate but I don't think age is important, the machine looks like it has never been used.
    Your point about blades being held in with set screws is the one that does concern me more than anything else, and if I decide to run it fast I would do some calculations first, all I can say, at the moment, is that I have never had a blade fly out of the manual machine.

    At this point in time I am totally undecided whether to run the thing around 6,000 or closer to 12,000 rpm. This will never be a highly used tool for me and I only want to make it once, so the safe way I guess, would be to opt for the lower speed range but the hot rodder in me is reluctant to accept that without some real data. Getting real data seems to be much harder than I expected. I have to decide soon because I promised to build a green house for her indoors. I have tools to do that job without the planer but it seemed to be the right motivation to get a tool going that I have had gathering dust for close to 10 years.

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