Solid Wood Machining

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

Post a Response
The staff at WOODWEB assume no responsibility for the accuracy, content, or outcome of any posting transmitted at any WOODWEB Forum. Participants should undertake the use of machinery, materials and methods discussed after considerate evaluation, and at their own risk.
Your Name:
Your Website:
Email Address:
Subject: Re: Molding/Shaper Knives

Message:

(read message guidelines).
Note: Do not use the below fields to advertise your business - only for links related to the discussion.
Thread Related Link URL:
Thread Related Link Title:
  To "point" to an image (picture) from another website, provide the URL (Web Address) of the file ( include ONE reference to http:// )
Thread Related Image URL:

Date of your Birth:

Upload a Thread Related File:
File Types: Image (gif-jpg-png-bmp), PDF, Sketchup, Video (mov avi wmv mpeg mpg mp4 ogg). (Image Upload Tips)

I have read the Site User Agreement and agree with the Terms

  <= Check to receive e-mail notification of responses

Message Thread:

Molding/Shaper Knives

2/18/23       
John Gault Member

I need to settle an age old technique argument that has persisted over the years and yet I can't come to grips with.

When setting a two knife shaper head there is an old school of thought to set one knife a notch lower than the other knife so that one knife cuts allowing the second knife to follow to "clean up" the cut.

I'm going to give my answer first and hope to get clarity.

I believe this technique works IF the first blade to BEGIN contact with the wood is the lower blade...otherwise IF the first blade to BEGIN contact with the wood is the higher blade then ONLY one blade is TRULY cutting. To me it's a 50/50 chance of this technique actually being effective.

What say you?

2/20/23       #2: Molding/Shaper Knives ...
D.Brown

I have always set my collar knives set ups as equal as possible.
IMHO only 1 knife hits the wood first the way I understand the other knives chop the waste smaller. So an example would be a 3 wing cutter they are all equal .

2/20/23       #3: Molding/Shaper Knives ...
aa

Line them up equally, only one is going to do the majority of the cutting anyways. It is impossible to obtain a perfect cutting circle unless using hydro heads and jointing.

2/20/23       #4: Molding/Shaper Knives ...
Matt Calnen

You’re the type of person that gets taken out Snipe hunting at night with a flashlight and pillow case!

Set your knives as even as you can.

2/21/23       #5: Molding/Shaper Knives ...
Brent

Yup, set the knives as even as possible. Depending on feed speed, DOC and how tight everything is, you will probably end up with one knife doing more than the other and determining the final outcome, but they will probably both be cutting and the lower knife will help the chip size etc. Also balance is a bit better if the radius of both knives is the same or close.

2/22/23       #6: Molding/Shaper Knives ...
Dustin J Orth

Unless you want to watch your shaper do a dance across the floor, ALWAYS set your knives equally in the head. Someone once told me that 1 gram of imbalance in a spinning head is equal to 22 pounds of force. Think about the center of balance in that cutterhead with knives not set equally. Dangerous is just the start, it could be deadly. As others have already mentioned one knife will do the cutting without hydrolock tooling and jointing stones. The difference between knives only needs to be .001 or more for a one knife finish.

2/22/23       #7: Molding/Shaper Knives ...
Jason

I’m guessing that lower by a “notch” is that you’re talking about a corrugation in the head? This would put one knife .030”+ out further than the other. Typically not considered a safe practice and as stated is a balance issue.
You really don’t want the lower knife to be more than .003” lower. The closer the better.
Think of it this way, the leading knife cuts even waves like in an ocean. The second knife clips the tip of those waves off. Not quite the perfect example but the closer the two knives are the better the finish and the less work and hp used by the shaper.

2/22/23       #8: Molding/Shaper Knives ...
D.Brown

One time I was tasked with reproducing some sort of siding that basically had a large raised panel cove cut and ship lap the other side. I did have some large collar knives in my collection and fired up an unmatched set, my PM 26 with a power feed vibrated across the floor and out of its foot print, it was the day I needed a change of shorts int he shop. Be safe.

2/24/23       #9: Molding/Shaper Knives ...
Adam

John,
I would question any other information that is provided by your "set one knife" lower person.

Knives set in a head are either jointed or non-jointed. Jointed doesn't mean they are ground in the same head. It means they are finish honed in that head. They are effectively the same geometry. Serious molding company will joint their heads.

In the case of non-jointed knives, which are the vast majority of knives. Some part of a knife is always protruding .001". It's not always the same knife. It could be half of one and half of the other. If you push one knife further down the head(parallel) the geometry totally changes again.

Do you purposely set your planer or jointer knives at different heights? Molding knives are the same cutting tool, just has more shape.

3/2/23       #10: Molding/Shaper Knives ...
Russ

Website: http://www.mr-moulding-knives.com/

John
I would agree with the posts about safety concerns.
The practice you're referring to is used by some folks to maximize the amount of linear footage they can obtain between sharpening. When the other protruding knife gets dull, they swap positions having a new knife to do the cutting. It's sometimes done among people that don't have a profile grinder. If both knives weigh the same, the cutter head itself is balanced, along with the gib screws and gibs, then it is statically balanced. However, the dynamic balance would be off by the offset; each cutterhead corrugation is typically 1/16" between one to the other.
I have attached a few articles that might help you better understand industry standards. As one post described, only one knife cuts when you line both blades up because of bore tolerance unless you use a hydraulic cutterhead and then joint them with a jointing stone.
It's all about safety, I always side with the best safety practices. I would always keep them in the same corrugation.

I hope that helps
Russ @ MR

https://www.mr-moulding-knives.com/information/moulding-knife-marks

4/28/23       #11: Molding/Shaper Knives ...
Rakesh Yves Member

The old school method can work if the lower blade is the first to hit the opponent. But since there is a 50/50 chance that this will work, it may not be the best way to get a clean cut.

 

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)
    Sponsors

    Become a Sponsor today!