Mill Stock for Muntins, Rails and Stiles(final)

Wood repairs for sashes, frames and sills.
Bob Yapp
Posts: 59
Joined: May 9th, 2011, 8:39 am

Mill Stock for Muntins, Rails and Stiles(final)

Postby Bob Yapp » March 8th, 2012, 8:10 pm

Number:
Status: [ ] submitted work method, [ ] proposed treatment standard, [x] final treatment standard
Update: 3/12/12
Author: David Gibney
References:
Contributors: Bob Yapp, John Leeke

Title of Treatment: Mill Stock for Muntins
Class of Treatment: [ ] Maintain, [ ] Stabilize, [x] Repair, [ ] Upgrade, [ ] Exception
Type of Treatment: [ ] Traditional, [x] Contemporary, [ ] Conservation

Condition to be Treated:
Sash parts that match originals are needed for repairs.

Description:
Mill lumber into muntin stock that exactly matches the existing muntins and can be used to renew missing or damaged muntins. This method is suitable for a small run of matching muntins, when not enough is needed to justify the time and expense of a shaper set-up. Consider making twice as many as needed for testing setups, mistakes and future window work. This method can also be used to shape the profiles of rails and styles. Assuming some of the original muntins, styles and rails still exist, they become patterns to work from. Study the original sash parts and joints closely.

Typical Procedure:

1. Document existing muntins by measuring overall dimensions, details and profiles. Draw the profile on paper showing shapes and dimensions.
2. Make a pattern for shaping the molding head cutters. The molding head for a table saw holds cutter at an approach-angle, usually a 35 degree angle, so take a piece of the original muntin and cut muntin at the same angle straight down from the top to create a pattern.
3. Transfer the interior curved profile of the muntin onto the blank molding head cutters by scratching or marking the face of the cutter.
4. Grind a cutter to the mark, using the same relief-angle as found on other cutters for that cutter head. Refine the contour of the cutter by holding it onto a piece of the original muntin (at the same approach-angle) to see where a little more may need to be ground off, creating a contoured cutting edge that matches the profile of the muntin exactly. Fasten the cutters into the molding head.
5. Select wood for the muntins that has very straight grain and no defects. For this procedure wood stock at least 3' long is needed, to safely run it through the molding head cutter mounted to a table saw.
6. Mill stock on the table saw to the overall finish width and thickness dimension of the muntins.
7. Install the molding head onto the table saw. Set up the fence and hold-downs. Always use hold-downs or feather boards for safety. Do a series of test runs with minor adjustments of the fence and height of the molding head, until the resulting cut matches up with the original muntin 100%. Pass each piece of stock over the molding head cutter twice, once for each side of the muntin. This will give the complete profile of the inside of the muntin. (not yet including the glazing rabbets.)
8. Do the production run, passing each piece of stock over the molding head cutter twice, once for each side of the muntins. This will result in the complete profile of the inside of the muntins. (not yet including the glazing rabbets.)
9. Set up the molding head and the table saw for cutting rabbets. Do a series of test runs with minor adjustments of the fence and height of the molding head, until the resulting cut matches up with the original muntin 100%. Pass each piece of stock over the molding head cutter twice, once for each side of the muntin. This will give the complete profile of the outside of the muntin, including the glazing rabbets.
10. Do the production run, passing each piece of stock over the molding head cutter twice, once for each side of the muntins. This will result in the glazing rabbets on the outside of the muntins. The milling of the muntin stock is complete.

(Making and fitting sash parts is beyond the scope of this individual standard; however the worker making this stock must understand how the stock will be used. To make muntins out of the muntin stock, cut the muntin stock to length and shape the joints at the ends of the stock. Study the original joints to learn how the joints work and the shapes that are needed. Matching the original joints, use a saw, coping saw and chisels to cut, fit and create new parts for the sash.)


Materials:
• Wood, decay resistant, very straight grain

Quality of Results

Best Work: 100% matching muntin profile in all dimensions and shapes. Tenons are snug with no gaps at joints.

Adequate Work: 100% match in overall dimensions, 80% match in profile of curves. Joints are snug with minor (1/32") gaps on no more that 50% of joints.

Inadequate Work: Wrong overall sizing, loose joints with gaps greater that 1/32".
Last edited by Bob Yapp on March 12th, 2012, 1:51 pm, edited 1 time in total.

johnleeke
Posts: 375
Joined: April 13th, 2011, 7:34 pm
Full Name: John Leeke
Location: Portland
Organization: Historic HomeWorks
Permissions: Yes
Location: Portland, Maine
Contact:

Re: Mill Stock for Muntins, Rails and Stiles (draft)

Postby johnleeke » March 12th, 2012, 11:10 am

This has some heavy editing and a few additions. Here is the original draft submitted by David and edited by Bob:

Number:
Status: [ ] submitted work method, [x ] proposed treatment standard, [ ] final treatment standard
Update:
Author: David Gibney
References:
Contributors:

Title of Treatment: Recreating Muntins
Class of Treatment: [x ] Maintain, [x ] Stabilize, [ x] Repair, [ ] Upgrade, [ ] Exception
Type of Treatment: [ ] Traditional, [x ] Contemporary, [x ] Conservation

Condition to be Treated:
Missing, rotted or broken muntins need to be replaced to match original. Not enough are needed to justify a shaper set-up.

Description:
This treatment is for a small run of matching muntins.

Typical Procedure:
1. Mill stock that is the same dimension as the muntins. Example: The average muntin 3/4" thick by 1-3/8” wide. For this proceedure wood stock at least 3' long. The length is needed to safely run them through the molding head cutter mounted to a table saw. Also consider making twice as many as needed for mistakes and future windows.

2. Because a molding head for a table saw is milling the muntin stock at a 35 degree angle, take a piece of an original muntin and cut it a 35 degree angle straight down from the top to create a template.

3. Transfer the molded contour (interior portion) of the muntin onto the blank molding head cutters.

4. Grind the blade to the contour of the molded profile of the muntin exactly.

5. Install the molding head cutter onto the table saw, make a test run with minor adjustments until the cutting action matches up with the original muntin 100%. Run both sides through the molding head cutter and this will give the complete profile of the top side of the muntin, (inside profile). Always use feather boards for safety. For the glazing bed side of the muntin (exterior), cut the rabbeted area with a dado blade.

7. This method can also be used to put the muntin profiles on rails and styles that are missing or beyond repair

8. Use a coping saw and chisels to cut and fit my new pieces for the sash. Assumingf you have some of the original muntins, styles, rails, they become your patterns to work from. Study the original parts closely.


Materials:
• Old growth lumber to match specie of original muntin. If old growth is not available use quartersawn new growth.

Quality of Results

Best Work: 100% matching muntin profile in all dimensions. Tenons are snug with few to no gaps at coping.

Adequate Work: Muntin is close but not exact in all demensions. Tenons are snug with a few fillable gaps.

Inadequate Work: Muntin doesn't look like or fit properly with stiles and rails. Sloppy tenons.
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com


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