Solid Wood Machining

You are not logged in. [ Login ] Why log in
(NOTE: Login is not required to post)

sloppy cope and stick joinery

1/7/14       
RC

So I have been wracking my brain/chasing my tail trying to sleuth what is going on.
Corrugated back cope and stick knives are creating very loose profiles. I have mic'd all grinds on the knife and they are right, and the knives are in the same cutting circle off the table

The procedure we use for installing is setting the head on the shaper table and dropping knives down into corrugations on top other steel knife blanks. I have been using this method for the past 13 yrs on this shaper and only on the past 2 jobs are we getting this result.

Another weird thing (that may point to some other problem)is that the groove in the stiles is tapered down into the bottom .
In other words to fit properly the tenon would need to taper out towards its end. Its hard to describe in words. See attached pic.I am thinking it is some kind of vibration, but the discrepancy is .010!
Thought maybe bent spindle, but it seems to be fine.

Has anyone had this ghost in their machine before?


View higher quality, full size image (2592 X 1936)

1/7/14       #2: sloppy cope and stick joinery ...
joiner Member

Wild guess here. Is it possible your machine shaft is bent and causing a a wee bit of wobble?

1/7/14       #3: sloppy cope and stick joinery ...
Dave

Is it possible your spindle isn't square with the table? You might try a straight edge between some spacers on the spindle and check it.

1/8/14       #4: sloppy cope and stick joinery ...
Russ

RC
It appears the profile has 90 degrees in the design, when re-sharpened they would have had to move the axial on the grinder to sharpen the vertical edge, thus changing the profile making it smaller in overall width of the dado groove.
It only works correct the first time, every time after the initial grind you will have to offset the knives to maintain the proper width of the groove.
In order to maintain the moulding knife correctly you would need to put a draft angle in the design of minimum two degree, this will enable the moulding knife to be sharpened correctly every time without having to offset the knives.

This is a dilemma all craftsmen that need 90 degree grooves are faced with, insert tooling would work best for this application.

I hope that helps explain what I see, maybe others will have more to add.
Contact info on my site if you need it.

1/8/14       #5: sloppy cope and stick joinery ...
Russ

Website: http://www.mirror-reflections.com

There are articles on my website that may help you get a better understanding about moulding knives.
Happy New Year!

1/8/14       #6: sloppy cope and stick joinery ...
Russ

Website: http://www.mirror-reflections.com

Please read article posted below, it the steel when cut was out of square as you may be getting two different reference points on the knives when placing the knives in the cutter head, causing the offset your experiencing making the groove bigger than needed.

Article

1/8/14       #7: sloppy cope and stick joinery ...
Russ

Website: http://www.mirror-reflections.com

RC
Here is a quick way to tell of your knives are offset creating too wide of a groove.
Remove cutter head with installed knives from shaper.
Lay cutter head on table on the rounded side (like you we going to roll it)
Place small straight edge on flat end of cutter head referenced side.
Measure from straight edge with calipers to one edge of the groove cutter.
Repeat procedure on other knife, you should find the offset.
Theory
Knives were out of square when cut, that's not the problem, referencing the knives before the initial grind was done is the problem. The initial reference point was ground away during grinding causing two different reference points on moulding knives.

1/9/14       #8: sloppy cope and stick joinery ...
JeffD

First thing I check is that the knives are in alignment with each other. When you drop and align on the table your trusting that the grinding was accurate and from the same end your bottoming out. Instead use a dial indicator to check the heights of a part of the profile of the knives with the head installed on the machine. I use one with a magnetic base so I can pop it on, check the knives and go!

If you find the knives are perfectly aligned I would then check the spindle for straight and square. Also make sure you have the spindle height locked in place when checking and running. I've found on some machines there's movement when locking the spindle down.

good luck,
JeffD

1/31/14       #10: sloppy cope and stick joinery ...
worwood Member

I have had that problem a few times, and when I did, it was always the bearings. When the machine is running, the bearings also would make more noise. It was like a hum. So I believe it was allowing the spindle to vibrate and wobble. That would be where I would start


Post a Response
  • Notify me of responses to this thread
  • Subscribe to email updates on this Forum
  • To receive email notification of additions to this forum thread,
    enter your name and email address, and then click the
    "Keep Me Posted" button below.

    Please Note: If you have posted a message or response,
    do not submit this request ... you are already signed up
    to receive notification!

    Your Name:
    E-Mail Address:
    Enter the correct numbers into the field below:
     

    Date of your Birth:



    Return to top of page

    Buy & Sell Exchanges | Forums | Galleries | Site Map

    FORUM GUIDELINES: Please review the guidelines below before posting at WOODWEB's Interactive Message Boards (return to top)

  • WOODWEB is a professional industrial woodworking site. Hobbyist and homeowner woodworking questions are inappropriate.
  • Messages should be kept reasonably short and on topic, relating to the focus of the forum. Responses should relate to the original question.
  • A valid email return address must be included with each message.
  • Advertising is inappropriate. The only exceptions are the Classified Ads Exchange, Machinery Exchange, Lumber Exchange, and Job Opportunities and Services Exchange. When posting listings in these areas, review the posting instructions carefully.
  • Subject lines may be edited for length and clarity.
  • "Cross posting" is not permitted. Choose the best forum for your question, and post your question at one forum only.
  • Messages requesting private responses will be removed - Forums are designed to provide information and assistance for all of our visitors. Private response requests are appropriate at WOODWEB's Exchanges and Job Opportunities and Services.
  • Messages that accuse businesses or individuals of alleged negative actions or behavior are inappropriate since WOODWEB is unable to verify or substantiate the claims.
  • Posts with the intent of soliciting answers to surveys are not appropriate. Contact WOODWEB for more information on initiating a survey.
  • Excessive forum participation by an individual upsets the balance of a healthy forum atmosphere. Individuals who excessively post responses containing marginal content will be considered repeat forum abusers.
  • Responses that initiate or support inappropriate and off-topic discussion of general politics detract from the professional woodworking focus of WOODWEB, and will be removed.
  • Participants are encouraged to use their real name when posting. Intentionally using another persons name is prohibited, and posts of this nature will be removed at WOODWEB's discretion.
  • Comments, questions, or criticisms regarding Forum policies should be directed to WOODWEB's Systems Administrator
    (return to top).

    Carefully review your message before clicking on the "Send Message" button - you will not be able to revise the message once it has been sent.

    You will be notified of responses to the message(s) you posted via email. Be sure to enter your email address correctly.

    WOODWEB's forums are a highly regarded resource for professional woodworkers. Messages and responses that are crafted in a professional and civil manner strengthen this resource. Messages that do not reflect a professional tone reduce the value of our forums.

    Messages are inappropriate when their content: is deemed libelous in nature or is based on rumor, fails to meet basic standards of decorum, contains blatant advertising or inappropriate emphasis on self promotion (return to top).

    Libel:   Posts which defame an individual or organization, or employ a tone which can be viewed as malicious in nature. Words, pictures, or cartoons which expose a person or organization to public hatred, shame, disgrace, or ridicule, or induce an ill opinion of a person or organization, are libelous.

    Improper Decorum:   Posts which are profane, inciting, disrespectful or uncivil in tone, or maliciously worded. This also includes the venting of unsubstantiated opinions. Such messages do little to illuminate a given topic, and often have the opposite effect. Constructive criticism is acceptable (return to top).

    Advertising:   The purpose of WOODWEB Forums is to provide answers, not an advertising venue. Companies participating in a Forum discussion should provide specific answers to posted questions. WOODWEB suggests that businesses include an appropriately crafted signature in order to identify their company. A well meaning post that seems to be on-topic but contains a product reference may do your business more harm than good in the Forum environment. Forum users may perceive your references to specific products as unsolicited advertising (spam) and consciously avoid your web site or services. A well-crafted signature is an appropriate way to advertise your services that will not offend potential customers. Signatures should be limited to 4-6 lines, and may contain information that identifies the type of business you're in, your URL and email address (return to top).

    Repeated Forum Abuse: Forum participants who repeatedly fail to follow WOODWEB's Forum Guidelines may encounter difficulty when attempting to post messages.

    There are often situations when the original message asks for opinions: "What is the best widget for my type of shop?". To a certain extent, the person posting the message is responsible for including specific questions within the message. An open ended question (like the one above) invites responses that may read as sales pitches. WOODWEB suggests that companies responding to such a question provide detailed and substantive replies rather than responses that read as a one-sided product promotion. It has been WOODWEB's experience that substantive responses are held in higher regard by our readers (return to top).

    The staff of WOODWEB assume no responsibility for the accuracy, content, or outcome of any posting transmitted at WOODWEB's Message Boards. Participants should undertake the use of machinery, materials and methods discussed at WOODWEB's Message Boards after considerate evaluation, and at their own risk. WOODWEB reserves the right to delete any messages it deems inappropriate. (return to top)


  • Forum Posting Help
    Your Name The name you enter in this field will be the name that appears with your post or response (return to form).
    Your Website Personal or business website links must point to the author's website. Inappropriate links will be removed without notice, and at WOODWEB's sole discretion. WOODWEB reserves the right to delete any messages with links it deems inappropriate. (return to form)
    E-Mail Address Your e-mail address will not be publicly viewable. Forum participants will be able to contact you using a contact link (included with your post) that is substituted for your actual address. You must include a valid email address in this field. (return to form)
    Subject Subject may be edited for length and clarity. Subject lines should provide an indication of the content of your post. (return to form)
    Thread Related Link and Image Guidelines Thread Related Links posted at WOODWEB's Forums and Exchanges should point to locations that provide supporting information for the topic being discussed in the current message thread. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related Link that directs visitors to an area with inappropriate content will be removed. WOODWEB reserves the right to delete any messages with links or images it deems inappropriate. (return to form)
    Thread Related File Uploads Thread Related Files posted at WOODWEB's Forums and Exchanges should provide supporting information for the topic being discussed in the current message thread. Video Files: acceptable video formats are: .MOV .AVI .WMV .MPEG .MPG .MP4 (Image Upload Tips)   If you encounter any difficulty when uploading video files, E-mail WOODWEB for assistance. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related File that contains inappropriate content will be removed, and uploaded files that are not directly related to the message thread will be removed. WOODWEB reserves the right to delete any messages with links, files, or images it deems inappropriate. (return to form)