A Fixture Board Strategy for Machining Small Parts
Posted: Tue Jul 20, 2021 3:07 pm
I define small parts to be 8 inches or less in length and width which represent a challenge to safely cut with a table saw, miter saw, or router and to a somewhat lesser degree for a bandsaw or drill press. That may be overly cautious for some but I have a healthy respect for what a spinning cutter can do to one of your fingers. A properly configured fixture board I believe is a great solution to this issue and the introduction of the ToolQuest line of products has made it even better. Rather than making this a long post I plan to break it up into several installments within this thread a few days apart to allow discussion among those who have interest.
Today I want to start with some of the things I have learned over the past year as an independent beta tester for ToolQuest. For those of you not familiar with ToolQuest please check out the website here. https://toolquest.net/
The products are very well explained there and I will not repeat it here. The emphasis of this post will be on a fixture board which may be implemented several different ways using traditional T-tracks, MatchFit dovetail slots and now the ToolQuest WoodAnchor slots. The WoodAnchor slot approach will be my focus. I have never received any compensation from ToolQuest for my testing and the opinions expressed here are totally my own.
One of the first things I did during my beta testing was extensive research into the best materials for WoodAnchor slot fixture boards. I found the very best panel material to be 1 inch thick industrial grade MDF sometimes referred to as Super MDF. It is more dense, rigid and heavier than standard MDF allowing it to maintain great flatness and stability even when several WoodAnchor slots are cut into it. A 4’x8’ sheet weighs so much I could not get it out of my truck by myself. I had to use a tracksaw in the truck bed to cut it into easier to handle 2’x4’ pieces. Also only a well stocked lumber distributor will carry it and the cost is about twice standard ¾” MDF so it might not be such a good solution for most folks. A more attainable solution is using contact cement to laminate standard ¾” MDF or standard 18 mm Baltic birch to ¼” tempered hardboard resulting in a 1” thick panel. If the slots are cut into the MDF or BB top side with the tempered hardboard on the bottom side I have found it to be just as stable as 1” Super MDF. Other materials that are close seconds to 1” Super MDF are 24 mm Baltic or Russian birch and ¾” Super MDF which also have limited availability and are pricy but are at least light enough to be manageable. Next comes standard 18 mm Baltic or Russian birch and finally standard ¾” MDF which are both readily available at a reasonable cost. I have not had very good luck with most other plywoods or MDO unless they are re-enforced at the bottom with a some type of cross hatch strips for support. Of course solid hardwoods like maple, oak or beech glued up into a panel work extremely well too but require a lot more work to use.
The first fixture board build I will discuss is one for my sliding miter saw. If I need to cut small parts I typically use the Incra Miter Express sled on my Shopsmith when accuracy/finish really matter or my bandsaw when I need something quick and dirty. Since it seems my Shopsmith is seldom setup in table saw mode it takes effort and time to configure and many times it disrupts the workflow on some projects that need repeated access to the drill press or drum sander. Dealing with this while one of the most accurate tools in my shop, a Kapex 120 sliding miter saw, sets idle is not very smart. However, without some type of additional holding capability for the parts it is far too dangerous to use for small parts. This is a perfect application for a fixture board and one using WoodAnchor slots and sliding nuts will be my preferred approach. The basic design should be general enough to work with whatever miter saw that you have so don’t tune out because you don’t have a Kapex.
Since I have some 1” Super MDF left over from my testing, I plan to use it for the base and fence but standard Baltic birch or MDF could also be used. Some design considerations include having enough slots in the right places for clamps and jigs but not so many that the structural integrity of the panel is compromised. Having one in the fence running the full length of the table seems valuable as is one not too far from the fence on the fixture board. Another thing that must be decided is how angled cuts will be performed. The saw can be rotated to make any cut +/- 45 degrees of the center line which is standard operation without the fixture board or it can be fixed on the center line and the work piece held at the desired angle of cut. I decided to hold the saw fixed on the center line and move the work pieces to the desired angle when using the fixture board. I don’t have a strong justification for it other than it just feels better when working with small parts and always knowing where the blade will cut by simply using the kerf in the table allows for a quicker setup. That being decided, slots about 3” from the center line on each side will be needed for holding and a couple of others distributed over the length of the table will finish the basic design as shown in the figure. I know that the slot placement seems kind of arbitrary but when you see the hold down fixtures and clamps it will make more sense. With a 1” table thickness I plan to set the depth stop on the saw at 7/8” to make a 1/8” kerf in the fixture board. At that blade height the fence will need to be a little over 1” wide to ensure complete cuts at the end of travel. I choose to just laminate two 1” thick strips 3” high to make the fence thickness an even 2”. That will limit my cut capacity from my normal 12” when no depth stop or fence are used to 9.25” with the 2” fence and 7/8” blade height. For small parts I think that is very acceptable.
With the basic design complete the next installment will cover the build and type of fixtures to used.
Today I want to start with some of the things I have learned over the past year as an independent beta tester for ToolQuest. For those of you not familiar with ToolQuest please check out the website here. https://toolquest.net/
The products are very well explained there and I will not repeat it here. The emphasis of this post will be on a fixture board which may be implemented several different ways using traditional T-tracks, MatchFit dovetail slots and now the ToolQuest WoodAnchor slots. The WoodAnchor slot approach will be my focus. I have never received any compensation from ToolQuest for my testing and the opinions expressed here are totally my own.
One of the first things I did during my beta testing was extensive research into the best materials for WoodAnchor slot fixture boards. I found the very best panel material to be 1 inch thick industrial grade MDF sometimes referred to as Super MDF. It is more dense, rigid and heavier than standard MDF allowing it to maintain great flatness and stability even when several WoodAnchor slots are cut into it. A 4’x8’ sheet weighs so much I could not get it out of my truck by myself. I had to use a tracksaw in the truck bed to cut it into easier to handle 2’x4’ pieces. Also only a well stocked lumber distributor will carry it and the cost is about twice standard ¾” MDF so it might not be such a good solution for most folks. A more attainable solution is using contact cement to laminate standard ¾” MDF or standard 18 mm Baltic birch to ¼” tempered hardboard resulting in a 1” thick panel. If the slots are cut into the MDF or BB top side with the tempered hardboard on the bottom side I have found it to be just as stable as 1” Super MDF. Other materials that are close seconds to 1” Super MDF are 24 mm Baltic or Russian birch and ¾” Super MDF which also have limited availability and are pricy but are at least light enough to be manageable. Next comes standard 18 mm Baltic or Russian birch and finally standard ¾” MDF which are both readily available at a reasonable cost. I have not had very good luck with most other plywoods or MDO unless they are re-enforced at the bottom with a some type of cross hatch strips for support. Of course solid hardwoods like maple, oak or beech glued up into a panel work extremely well too but require a lot more work to use.
The first fixture board build I will discuss is one for my sliding miter saw. If I need to cut small parts I typically use the Incra Miter Express sled on my Shopsmith when accuracy/finish really matter or my bandsaw when I need something quick and dirty. Since it seems my Shopsmith is seldom setup in table saw mode it takes effort and time to configure and many times it disrupts the workflow on some projects that need repeated access to the drill press or drum sander. Dealing with this while one of the most accurate tools in my shop, a Kapex 120 sliding miter saw, sets idle is not very smart. However, without some type of additional holding capability for the parts it is far too dangerous to use for small parts. This is a perfect application for a fixture board and one using WoodAnchor slots and sliding nuts will be my preferred approach. The basic design should be general enough to work with whatever miter saw that you have so don’t tune out because you don’t have a Kapex.
Since I have some 1” Super MDF left over from my testing, I plan to use it for the base and fence but standard Baltic birch or MDF could also be used. Some design considerations include having enough slots in the right places for clamps and jigs but not so many that the structural integrity of the panel is compromised. Having one in the fence running the full length of the table seems valuable as is one not too far from the fence on the fixture board. Another thing that must be decided is how angled cuts will be performed. The saw can be rotated to make any cut +/- 45 degrees of the center line which is standard operation without the fixture board or it can be fixed on the center line and the work piece held at the desired angle of cut. I decided to hold the saw fixed on the center line and move the work pieces to the desired angle when using the fixture board. I don’t have a strong justification for it other than it just feels better when working with small parts and always knowing where the blade will cut by simply using the kerf in the table allows for a quicker setup. That being decided, slots about 3” from the center line on each side will be needed for holding and a couple of others distributed over the length of the table will finish the basic design as shown in the figure. I know that the slot placement seems kind of arbitrary but when you see the hold down fixtures and clamps it will make more sense. With a 1” table thickness I plan to set the depth stop on the saw at 7/8” to make a 1/8” kerf in the fixture board. At that blade height the fence will need to be a little over 1” wide to ensure complete cuts at the end of travel. I choose to just laminate two 1” thick strips 3” high to make the fence thickness an even 2”. That will limit my cut capacity from my normal 12” when no depth stop or fence are used to 9.25” with the 2” fence and 7/8” blade height. For small parts I think that is very acceptable.
With the basic design complete the next installment will cover the build and type of fixtures to used.