MagicFence Anyone - Looking for opinions

[Sam Bhanji]

Hello Fellow Creekers,

I am looking into a project of designing and producing a computerized precision table saw fence system that can be driven and positioned by a computer (or tablet) using software. In order for it to be competitive, I was thinking of using a precision lead screw that can be driven using a stepper motor. My initial thoughts are to provide a downloadable copy of the driver and software that can be installed on any WIN system (or tablet) using a USB port to send the appropriate signals out to the controller for positioning commands.

Before I dive too deep into this, I wanted to get an opinion whether such a precise positioning fence would be something of interest. I am targeting to to keep the cost as low as possible to make it affordable compared to what good fences cost these days :-)

Any opinions/feedback much appreciated. If there is much interest than I will post my progress and designs as time permits :-)

Thank you all,
Sam.

[Carl Carew]

Sam before you read my comments you should know that I am the guy who said "what are they thinking of, trying to sell water in a soda bottle". But I am a design engineer with a post grad degree in mechanical engineering. My first reaction is that most table saw work doesn't need that level of precision and the woodworking shop is not the environment for your computer. That said I would strongly advise you to go ahead and build your prototype even use the computer for the prototype. Once you get it working I would look into adapting an existing microprocessor to replace the computer. The experience you gain from this will help you adapt your concept to other applications as well. I have trouble getting the vertical adjustment just where I want it on my shaper, particularly when cutting rails and stiles. You might have an application there

Good luck
Carl

[Matt Day]

I'd be intersted in seeing more, but here are a few comments.

will the screw be enough to lock the fence?

Regarding safety, there should be someway to stop the fence from accidental movements during cuts.

I don't have my computer or tablet in my shop, but I always have my phone. A smart phone app would be more attractive to me rather than computer/tablet.

You're competing with the simple add on gadget that displays the position of the fence. And my gut tells me that there is a relatively small market for something like this in the hobby realm.

[Phil Barrett]

I also think you should make a prototype.

WW doesn't need extreme precision but it does need a reasonable level of precision. When I want a 9" rip, I want it to be within at least 1/64th, closer is better. I don't think you need a super precision lead screw. A standard stepper motor has 200 steps per rotation and with a 16 TPI screw you get 1/3200" per step. Getting down to single digit mils accuracy is a bit misleading because wood is fairly "plastic".

Yes, locking is super important. I think you just have to try it. My guts says that leadscrew and drive nut will be pretty resistant to axial forces but that needs to be proven. A lot depends on where the leadscrew drives the fence. A locking clamp will add cost, of course.

Here's a problem that I think your approach could also solve - fence offset. I often add an auxiliary fence or block. That requires that I have to add the aux fence width to the gauge. While that's not a big deal, accuracy is lost (well, maybe challenged is a more apt term) in that you need to know the exact width of the fence. Having some automatic way of determining offset would be of value to me. Right now the standard approach is to "kiss the blade".

Repeatability is obviously an important feature. I'm sure you know that, though.

As to using a computer/tablet/phone. Physical connections are problematic in the shop. Blue tooth makes more sense but I agree with Carl that you should have a self-contained control unit. Requiring some other device to control the table saw is going to be problematic (what if my tablet dies or I leave my phone at work or ...).

Finally, one of the reasons I don't have an Incra fence on my TS is that it takes up WAY too much space. Solve that and I might be a customer.

By the way, in any product design process, you should look at your competitors and do a feature matrix. This often reveals how you can be competitive. Hope you have done that.

[Rod Sheridan]

Sam, there are many saws with digital motorised fences available from the saw manufacturer.

I believe there is a Tiger Stop refit fence on the market also?

You may want to look at what's available commercially.

Regards, Rod.

[Bill Huber]

I have a digital read out on my table saw and use it all the time, it calibrates really fast so if I put on my stop on the fence I just recalibrate it in a flash. The same goes with my aux fence, just recalibrate and I am ready to go.

One of the things that has to be with any type of digital read on a fence is the fence has to be able to be taken off and put back on really easy. With mine I can take the fence off and put it back on just like I didn't have the read out on it, I don't have to recalibrate it or anything, just pull the unit away from the fence.

The other thing to me is speed, if my fence is setting at 3" and I want to get to 20", I just move it and it is read, I don't have to wait for a stepper motor to do it.

I also agree that it should be a self-contained unit, I do not have a computer in my shop.

[Matt Day]

Very good points Bill. I agree 100%.

What digital device do you use?

[Bill Huber]

Very good points Bill. I agree 100%.

What digital device do you use?

I have the Wixey, I thought it was a gadget when I first saw it and then when they had a sale I got one and wouldn't be without it now.
Just last week I was cutting 6 dados in the same board, they were 2 1/8" apart, with the Wixey it was a snap, cut a dodo, hit the button to Inc and move it 2 1/8" cut it and move, it was so easy.

[Peter Aeschliman]

My thought...

Consumers are brutal. They often say they want something, but when it comes time to plunk down cash, you find out they don't want it after all. So at this stage, if you are planning on making this a commercial endeavor and not a hobby, be shrewd and objective before putting much money into it.

First identify what segment of consumers or professionals will want it and talk to them. A lot of them. Survey people. Collect data. Do research. Analyze product substitutes both in terms of cost and function. Identify the problem that needs solving, and build a product that solves that problem.

In this case, I worry that the old saying "it's a solution looking for a problem" comes to mind. Digital fences are relatively inexpensive and serve the same function. The only difference is that the user must move the fence manually. So when you talk to your target customers, I recommend asking them how much of a pain physically moving the fence is. If they say it's not much of a hassle at all and it's more about measuring accurately, then do the shrewd thing and don't proceed with this as a commercial endeavor.

[Sam Bhanji]

Thank you all for your feedback and comments. I do agree that moving along with a prototype does make sense, if all fails I will still end up with something functional for myself. Some of the things I was looking for on this project is:

1. Precise repeatability
2. I would think that punching the absolute length on a keypad to position the fence be quicker than measuring twice, cutting once :-)
3. Lockable fence and lead-screw support to keep it strong during cuts
4. Ability to mount a small SBC (single board computer using SDCard) in a protected panel with 7" LCD
5. A quick connect platform that is easily moved/removed
6. I am debating whether to incorporate V-groove bearings at each end of the fence since they have been used/tested in such an environment on shopbots and others

These are just some of my thoughts... I am working a design sketch that I will be posting for feedback this week. I have access to a CNC machine that I am hoping will make my machining tasks easier :-)

Thanks,
Sam.

[richard poitras]

I would love to see your prototype once its done...

[Rod Sheridan]

Thank you all for your feedback and comments. I do agree that moving along with a prototype does make sense, if all fails I will still end up with something functional for myself. Some of the things I was looking for on this project is:

1. Precise repeatability
2. I would think that punching the absolute length on a keypad to position the fence be quicker than measuring twice, cutting once :-)
3. Lockable fence and lead-screw support to keep it strong during cuts
4. Ability to mount a small SBC (single board computer using SDCard) in a protected panel with 7" LCD
5. A quick connect platform that is easily moved/removed
6. I am debating whether to incorporate V-groove bearings at each end of the fence since they have been used/tested in such an environment on shopbots and others

These are just some of my thoughts... I am working a design sketch that I will be posting for feedback this week. I have access to a CNC machine that I am hoping will make my machining tasks easier :-)

Thanks,
Sam.

Those are all good parameters Sam.

How about interfacing with a central controller to cut parts in a stack list?

You really should look at the range of existing digital fences on saws to see what features are required by commercial users.

One useful feature would to be able to incorporate the 3 function rip fence into the digital design.......Rod.

[Michael Moscicki]

http://www.rockler.com/ready2rout-router-table-fence

http://www.rockler.com/touch-screen-controller-unit-for-ready-2-lift

http://www.rockler.com/ready-2-lift-router-lift

I don't know if this is what you would be interested in doing, but for a table saw instead of a router table. It is essentially a touch screen device that controls the movements of the router fence and router lift. The router fence comes with the touch screen device, but you could buy the touch screen device separately for use with a router lift.

Here is a review of the fence:
https://www.youtube.com/watch?v=CeOX8twaefA

[Sam Bhanji]

Hello Creeker's,

Finally has some time to put my thoughts on paper. I am attaching the initial design concept hopefully it will provide some basic information to garner additional feedback. Most of the structure components can be easily sources using aluminum extrusions that are readily available and anyone can purchase. My intention is to make this as affordable as possible for everyone :-)

Keeping it affordable is easier said than done so what I was thinking is of putting together a kit form by providing the lead-screw enclosure, motor, controller and software that can be putting together in various configurations.

302007

Thank you all for you feedback,
Sam.

[Matt Day]

Looking good! Remember to take into account fence alignment and adjustment.

Any way to make it work as a fence for both table saw and router table, for those of us that have a RT mounted in the extension wing?

[Craig Hoehn]

I don't want to discourage you because it sounds like a fun project for yourself, and it would be nice to have, but there are companies that already make table saws with this feature such as Felder, Format 4, Casadei, Martin, Altendorf, and I'm probably forgetting a few. Granted all of these saws are expensive, but if you look at the price of a nice table saw plus an electronic fence it probably wouldn't be too far off just buying a table saw that comes with this feature from the factory.

[Sam Bhanji]

I am thinking of making it available in a few different sizes to fir various configurations and tables.

Sam.

[Sam Bhanji]

Hello Craig,

Point noted, I am hoping that a lot of us would be able to retrofit our existing saws than to replace them at a cost over 4k. While I have not put together a complete BOM since I am still at the design stage. I will share some numbers as soon as I start prototyping. I would love to see the kit (lead-screw module, motor, controller and software) being offer for no more than few hundred. If it does not materialize, I still have a fence system :-)

Sam.

[Chris Merriam]

Seems like a digital version of the Incra fence, subject to the same setup requirements: you need to allow for parallel adjustment of the motor mount to the rails. Incra does this with four or eight locking screws per side. Then to lock the fence itself they include clamps at the front and back. You might want to read thru some of the Incra setup documents.

[Art Mann]

I don't understand the drawing. I assume there is supposed to be a lead screw inside the square tube with a stepper motor at one end and the fence at the other end. Where is the lead screw going to go when the fence is moved? It can't stick out past the fence and it can't move in the other direction because of the location of the stepper motor. The drive mechanism is going to have to be a good deal more complex than you show. What is going to keep the fence parallel to the miter slot? What you have illustrated there is certainly not going to do it. If there is a guide and rail system like a normal table saw that is supposed to hold the fence parallel, then the drive mechanism needs to be driven at the end with the guide rather than in the middle. Otherwise, you are going to get racking and binding at the least little amount of friction as the fence is moved back and forth. You may, in fact, need two lead screws on each end that are driven together to hold the fence steady and perpendicular to the direction of travel.

What you are trying to do is certainly doable. You could probably buy most of the parts from a company called CNC Router Parts, which sells components and kits for building CNC routers. The rest of it could be fabricated out out of extruded aluminum rails (Google "80/20 rail" to see what I mean) and a few precision machined parts. However, I think you greatly underestimate the amount of engineering, machining and precision fabrication needed to create a working machine. I don't mean to discourage you but I think you have a lot of homework to do before you start spending any money.

[Sam Bhanji]

Thanks Chris, yes, the design while not detailed on what I posted will allow the lead-screw frame to be adjusted up/down parallel to the rails easily using a square.

Sam.

[Sam Bhanji]

Hello Art Mann,

Thank you for your feedback and yes, I agree with what you have shared. From what I have been able to research the deflection you mention about can be solved in one or more of the following ways:

1. Mount the leadscrew base closer to the fence to minimize deflection - the rear base of the platform supporting the leadscrew can be positioned closer to fence to support that

2. Add rail and bearings at each end of the fence to minimize friction and force required to command the positioning of the fence - its something I have called out and will test to see if required

3. Support the fence using a motor at each rail as you have mentioned so they can work in unison to position the fence

I do expect to make improvements as I start prototyping and for sure the design concept I have shared will change. I am hoping to strike a balance between the level of precision, engineering and cost to make it affordable. I have looked at the INCRA fence, and they have been able to drive the precision required for the woodworking community with a single leadscrew from what I can tell.

Thanks,
Sam.

[Frederick Skelly]

I feel like some old time craftsman looking at an electrified tool for the very first time and saying "what do I need THAT for?" :) [Edit: My point being that the craftsman couldnt possibly have predicted how the market for electic tools would grow with time, even though HE himself didnt need them.] While I wouldnt buy one myself, MANY people enjoy having/using the latest and greatest application of technology. They just enjoy using Tech. (Oddly, I find myself going the other way and moving into hand tools while using my machines less and less.) So Id build your prototype and maybe give a few away as door prizes to woodworking clubs, shows, SMC "free stuff" drawings, etc just to gauge reaction and build interest. I do have two ideas for you, since we're sort of serving as a marketing clinic for you:
* Id definitely offer it as a kit first. Thats genius! It keeps your cost and the consumer's cost down.
* Make sure your software provides the capability for the owner to increase the font size. That seems silly, but it could become a selling point, expanding the market to middle age and retired woodworkers whose eyes arent what they once were.

Best of luck to you!
Fred

[Sam Bhanji]

Hello Frederick,

Thank you for the feedback. Thats a great point you made regarding font size. I am working on a sketch of the interface and will post it soon with some of the functions and capability of the operations that can be performed.

Sam.

[Ted Reischl]

I would never buy one myself, but hey, there are folks who are more than likely looking for something with this functionality.

Why a lead screw? As someone mentioned before that screw has to go somewhere and the way you have it designed it is trapped. Using a lead screw means you will be adding at least the length of the travel to the footprint of the machine (the screw will hang out over the right side).

From just a cursory look at this, it seems to me that no matter how you design it the footprint of the saw will increase by at least the amount of travel desired. For instance, my TS is about 72 inches overall. It has 32 inches of fence travel to the right. My machine would need at least 105 inches of footprint with a drive attached to it.

If you look at commercial saws of this type you will see that they put the fence drive mechanism under the table. You might be able to do that, or not.

[Sam Bhanji]

Hello Ted,

You are correct in that the footprint of the saw with maximum use will be extended. When designing I was trying to be creative how to solve for that but the challenge was that the more creative I got, the more I had to know all the various saw configurations out there so in order to keep it generic (to fit most saws in the market), I had to position it where it is. Nothing says that for future revisions of the design that this cannot change but I would rather keep it simple for the initial prototype.

Thank you for question that,
Sam.

[John Coloccia]

That design is not workable, if for no other reason that it doubles the footprint required since the lead screw (or whatever) will have to go somewhere when the fence moves to the right. That's an absolute non-starter in most shops. A better design would be a linear rail and screw on one side. There's really no reason to have anything at all on the other side, like a Biesemeyer style fence, and that will solve a lot of alignment problems. If both sides are constrained, they will have to be very parallel, and that's probably not going to happen as a retrofit without a LOT of work. Also be aware that you will need some way to easily remove the fence, or at a minimum at least be able to flip it out the way (flipping out of the way takes up a lot of room, again). It's a non-starter to not be able to do a long crosscut.

This is all very doable, but I have a lot of experience with controls and automation, and my gut tells me that you will need heavy duty linear rails to pull it off, or perhaps a combination rail/linear motion drive unit. I believe the cost will end up being prohibitive. That's my opinion.

[Sam Bhanji]

The linear rails will definitely be my last resort if it has to come to that - they are also not very conducive to the woodworking environment unless they are well protected which increases the cost as you mentioned. I will keep you posted.

[John Coloccia]

The linear rails will definitely be my last resort if it has to come to that - they are also not very conducive to the woodworking environment unless they are well protected which increases the cost as you mentioned. I will keep you posted.

You can leave them exposed if they have wipers. We use them all the time on CNC machines with no problems at all. That said, it's just a little bit of sheet metal to make a cover so there's no reason not to.

[Frederick Skelly]

Hello Frederick,

Thank you for the feedback. Thats a great point you made regarding font size. I am working on a sketch of the interface and will post it soon with some of the functions and capability of the operations that can be performed.

Sam.

Hey Sam, another thought for you: be careful how much of your design you post on this and other web pages. Crowdsourcing can be a good way to gather ideas, but if you go too far someone can steal your designs. Also, depending on terms of service on a given site and the "attitude" of its proprietors, it seems possible that you could unintentionally be granting some intellectual property rights to the site owner. Im just theorizing, but I know more than one website that publishes web-provided shop tips in their magazine and/or sells DVDs of selected website content.
(It would suck to come up with the next great product, be making a lot of money and have someone else sue for a piece of your action.) Again, I dont have proof of this - Im just saying to watch out for your own interests.

Fred

[Sam Bhanji]

Thanks Fred, great point :-)

[Sam Bhanji]

Yes, definitely agree.