Need advice resurfacing a 20" X 40" cast iron wood planer bed .006 out-of-flat (job)
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    Default Need advice resurfacing a 20" X 40" cast iron wood planer bed .006 out-of-flat (job)

    Need advice resurfacing a 20" X 40" cast iron wood planer bed .006 out-of-flat (job offering):

    A friend with a furniture making company has a large wood planer with a worn bed. He needs it flattened. He either needs to find someone to do the work or find a way to do it in-house. He can remove the bed to do the work or leave it in place and remove all components above it for full access. Essentially, how would you go about resurfacing a 20" X 40" cast iron planer bed that is about .006" out of flat? The resulting surface has to be within .001" of perfectly flat [reason for that is that there are levelling rollers that stick up .001" above the bed]. He needs about 4-5 days turnaround to get the work done. Is there anyone within 500 miles of Chapel Hill NC USA who could do this job? Would facemilling it on a large mill produce a surface within the .001" tolerance? Should it be scraped? hand ground with diamond stones? wet-dry sandpaper? side grinder :=( belt grinder :=(. This is obviously a job for a planer.
    Any help or offers to do the work would be appreciated. I'll put you in touch with my friend.
    LFLondon

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    You could find somebody to plane, surface grind or blanchard grind it.

    This has been done before by many others.

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    If it were me I would have it scraped in position without moving it. To expect to send that out and have it machined to within .001 and then ship back and reinstall and have it still within .001 total flatness is asking a lot.

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    I had mine Blanchard ground. It worked just fine. Bob

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    Quote Originally Posted by Joe Miranda View Post
    If it were me I would have it scraped in position without moving it. To expect to send that out and have it machined to within .001 and then ship back and reinstall and have it still within .001 total flatness is asking a lot.
    The best approach by far. The reason for this is you have no idea what the .006 will be when you unbolt it and take it out of the planer

    Scraping will also have the least tool pressure of any of the processes mentioned

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    How is the table mounted,Bolts? If so it should be torqued down to mimic hows it mounted in the machine similar to torque plate for automotive heads. Your asking alot to achieve .001 over 40"

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    Quote Originally Posted by johnoder View Post
    The best approach by far. The reason for this is you have no idea what the .006 will be when you unbolt it and take it out of the planer

    Scraping will also have the least tool pressure of any of the processes mentioned

    Thanks, John. He is an expert woodworker but has no experience with any machining processes. I agree that scraping would be best but he would have to do it himself or find someone willing to do the job who knows what they are doing. I thought there might be a PM'er who would want this work. I think he would pay a fair price to get it done. He is buying a new helical cutter head for the machine so this is a high priority job.

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    Quote Originally Posted by redlee View Post
    How is the table mounted,Bolts? If so it should be torqued down to mimic hows it mounted in the machine similar to torque plate for automotive heads. Your asking alot to achieve .001 over 40"
    Yes, bolted down and the plane of the bed is adjustable side to side. I had doubts about achieving .001 tolerance after removing and machining it so flattening it in place seems to be the best way to do the work, by far. If it were mine I would dedicate the time to learn how to scrape, buy the tools, buy several diamond flattening plates (used to sharpen tools and flatten stones) and do the work myself. He could at least improve it this way. A previous owner tried to flatten the bed with a hand held random orbit sander and left interesting artwork behind. He needs to do this work when he installs a new helical cutter head for the machine.

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    keithmech Guest

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    you realize that .006 is slightly more that the thickness of a piece of paper.?How was this measured over an area 800 square inches?
    Why not just more the leveling rollers up .005?

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    When the bed gets back in shape tell your friend to alternate the position on the bed as he feeds pieces of wood. That way the bed will stay relatively flat and he might never have to mess with it again.

    The same alternating patterns should be done with a jointer. With both methods the knife and bed wear is somewhat evenly distributed. It's about the best one can do and I take advantage of it.
    Last edited by rons; 10-18-2017 at 02:30 PM.

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    Quote Originally Posted by LFLondon View Post
    Need advice resurfacing a 20" X 40" cast iron wood planer bed .006 out-of-flat (job offering):

    A friend with a furniture making company has a large wood planer with a worn bed. He needs it flattened. He either needs to find someone to do the work or find a way to do it in-house. He can remove the bed to do the work or leave it in place and remove all components above it for full access. Essentially, how would you go about resurfacing a 20" X 40" cast iron planer bed that is about .006" out of flat? The resulting surface has to be within .001" of perfectly flat [reason for that is that there are levelling rollers that stick up .001" above the bed]. He needs about 4-5 days turnaround to get the work done. Is there anyone within 500 miles of Chapel Hill NC USA who could do this job? Would facemilling it on a large mill produce a surface within the .001" tolerance? Should it be scraped? hand ground with diamond stones? wet-dry sandpaper? side grinder :=( belt grinder :=(. This is obviously a job for a planer.
    Any help or offers to do the work would be appreciated. I'll put you in touch with my friend.
    LFLondon
    .
    .
    cnc milling machines sections weighing tons to .0005" flatness and perpendicularity tolerance is routine and done every day.
    .
    its not always shiny mirror finish like shown but as long as it measures waviness of .0003" TIR or less its usually ok for most things
    .
    gravity requires how part is setup in machine to be important. it is very easy for part to sag or distort just by how it is setup in a cnc mill
    Attached Thumbnails Attached Thumbnails shinymilling.jpg   bn25a_partsnearby_smaller.jpg  

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    Quote Originally Posted by keithmech View Post
    you realize that .006 is slightly more that the thickness of a piece of paper.?How was this measured over an area 800 square inches?
    Why not just more the leveling rollers up .005?
    Adjusting the levelling rollers won't do what he needs, it seems. He is getting imperfect planing on costly boards for pricey furniture and it is serious enough for him to have the bed flattened. I have no idea how he measured the sag. I found some machinists in a Facebook group who supplied a list of shops in North Carolina that might be able to do the work. My guess is that he could at least gain some improvement over what he has now.

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    many shipping port cites cause they repair ocean ships have big equipment and often it there unused for large lengths of time.
    .
    picture of 7 story tall sea container ship being launched that day. that ship yard had equipment to deal with 40 foot long parts. they as long as there is no rush will accept small jobs to keep the machines busy.
    .
    really when you are used to small city or town and you go to big shops like that you come away with feeling like your small potatoes surrounded by giants
    Attached Thumbnails Attached Thumbnails ship_b.jpg  

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    keithmech Guest

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    what type of planer is this?

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    Some plainers have raised areas on the sides. If this one does, that takes out Blanchard grinding. How much work to remove the table? How accessable is the part of the table near the cutter head?

    Pictures are in order.

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    Quote Originally Posted by LFLondon View Post
    Need advice resurfacing a 20" X 40" cast iron wood planer bed .006 out-of-flat (job offering):

    A friend with a furniture making company has a large wood planer with a worn bed. He needs it flattened. He either needs to find someone to do the work or find a way to do it in-house. He can remove the bed to do the work or leave it in place and remove all components above it for full access. Essentially, how would you go about resurfacing a 20" X 40" cast iron planer bed that is about .006" out of flat? The resulting surface has to be within .001" of perfectly flat [reason for that is that there are levelling rollers that stick up .001" above the bed]. He needs about 4-5 days turnaround to get the work done. Is there anyone within 500 miles of Chapel Hill NC USA who could do this job? Would facemilling it on a large mill produce a surface within the .001" tolerance? Should it be scraped? hand ground with diamond stones? wet-dry sandpaper? side grinder :=( belt grinder :=(. This is obviously a job for a planer.
    Any help or offers to do the work would be appreciated. I'll put you in touch with my friend.
    LFLondon
    Scraping is an option, but finding a suitable master may be a big issue. a 20"x40" is almost like scraping a surface plate. It is not impossible but pretty daunting. Assuming that he stated that it is out of flat 0.006" he already has a way of measuring the flatness at least in one dimension. There are some scraping videos of large surface plates that could help with methods to verify flatness using smaller plates and straight edges. A 4' camelback SE and a 12"x18" surface plate for local flatness is used in many case. If you need flatness below 0.001" you probably need to use an optical collimator. The planer bed may not have enough rigidity to maintain flatness to beyond 0.001". If you have a 3'x4' surface plate then you could direct spot it. how much does the darn thing weigh? Scraping 0.006" off the entire surface is a lot of scraping .

    Curious how the error manifest itself in the planed lumber? An error of 0.006" across the 20" is probably very noticeable, but i do not know how that would manifest in the direction of 40". Wood is rather compliant and gets pressed into a 0.006" dish. It may be sufficient to make sure that the plate is flat across just under the knives.

    I think grinding is a better option .


    dee
    ;-D

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    Quote Originally Posted by keithmech View Post
    what type of planer is this?
    It is a large Powermatic made about 1960, 3 phase.

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    Quote Originally Posted by gbent View Post
    Some plainers have raised areas on the sides. If this one does, that takes out Blanchard grinding. How much work to remove the table? How accessable is the part of the table near the cutter head?

    Pictures are in order.
    Well, this is a non paying job for me and the shop is way down the road so cannot supply pix. I suggested the owner get a PM account and take a dive into the lion's den.
    Yes, it does have raised sides, about .5". Its not that much work to take the table out or remove components overhead to work on the bed in place. He is planning on doing this. The machine is quite valuable to his business.

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    Quote Originally Posted by dcsipo View Post

    Curious how the error manifest itself in the planed lumber? An error of 0.006" across the 20" is probably very noticeable, but i do not know how that would manifest in the direction of 40". Wood is rather compliant and gets pressed into a 0.006" dish. It may be sufficient to make sure that the plate is flat across just under the knives.

    I think grinding is a better option .


    dee
    ;-D
    I agree with the grinding being the better option.

    Normally when tables wear, it manifests itself as "snipe" in the work; the wood is happily running through the planer supported by the feed rollers, then as the end comes off the roller, it drops down because the table isn't there to support it. It affects the last six or so inches, whatever the distance is between the infeed roller and the cutterhead. With no support, the last six inches gets a rippled effect as the end of the board bounces up and down. While it's no great shakes with common framing lumber, you can see where one wouldn't want to have to add six or more inches to each length of exotic hardwood.

    Biggest problem with scraping is the wear is going to be localized; which means 90% of the surface needs to be taken down. The machinery builders grind these tables, shouldn't be any reason not to recondition them on a grinder. They typically are supported on either wedges or leveling bolts, so any bow or twist can be taken out.

    Dennis

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    Quote Originally Posted by LFLondon View Post
    Well, this is a non paying job for me and the shop is way down the road so cannot supply pix. I suggested the owner get a PM account and take a dive into the lion's den.
    Yes, it does have raised sides, about .5". Its not that much work to take the table out or remove components overhead to work on the bed in place. He is planning on doing this. The machine is quite valuable to his business.
    Get a 13" portable for a backup, and send out the table to someone with a large surface grinder or a planer. because of the integral ledges you cannot blanchard grind it, it would also be a bit complicated to scrape it as well for the same reason.

    Powermatic 221 2" Straight Knife Planer | The Equipment Hub



    dee
    ;-D

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