Material Hold Downs, Jigs and Things

[srwtlc]

I wanted to start this thread for two reasons.
1)To discuss various ways that we have come up with to hold down material for cutting, mainly odd or small parts, by use of various jigs or the like. (Happiness is a well made jig that works well) ;^)
2)I have need of ideas on how to hold some 5" x 7" blanks to cut a circular pocket in the middle, trim, radius the corners, and round over the edges of them with an ovolo bit.

Because of not being able to hold them from the top, and vacuum not being strong enough without edge contact, the one way I keep coming back to is to screw them to a backer board using a template for alingment then placing the screwed down group on the table in the same place every time by indexing it. I have to do 700 of these so I'd like to come up with something quicker than two screws in each blank. Anyone have some other ideas?

I'll make my contribution to the jig discussion with my jig for holding blanks for boxes that consist of two 5" x 8" x 3/4 pieces, one is the top with a deep recess and one is the bottom with a shallow recess that gets either a pocket for a badge, knife, etc. My jig is a two-part jig that is sandwiched together. The top layer is 3/4" thick that has 20 shallow 5" x 8" pockets in the top with a slightly smaller rectanglar hole all the way through. This layer is on top of another piece of 3/4" material that has a manifold cut in it connecting all the openings to vacuum from a shopvac. This setup works very good for this type of project with a master file that allows me to place any type of pocket or whatever in all 20 pieces quickly.

So how about it, any other ingenious jigs or methods out there? Any suggestions for my other project?

Scott

[gerald_d]

Scott, your 5" x 7" problem:

What material? How thick?

If, for example, they are pine and 0.5" thick, we would cut them out of 6" x 0.75" planks. Hold the plank down with 2 G-clamps, cut everything 0.6" deep (in a very careful sequence), then run plank through a thicknesser to remove the bottom skin.

[davidallen]

one trick I use when machining metal is hot melt glue. the piece to be cut is glued to an oversize metal plate. the metal plate is then fixed to the table in any convienent fashion. after cutting, the metal plate is warmed enough to release the glue and the part is removed.

if you have a finished back side, the glue may be hard to remove. if it's a felt back, after sanding and finishing the front, the felt can be ironed on with the residual glue.

[rgengrave@aol.com]

Scott I use T-Track, I can hold anything from 1"x1" to 6 inches tall.
With T-Track you do not need a vacuum table or any other hold downs, you will be able to cut all the way thru the material too without it ever moving.

Ron V

[steve]

what about the plastic nails fired in from a nailgun instead of the screws?

[jorgy.tucson@worldnet.att.net]

Add additional cutting zones (1 to 3)so the router never stops while you change parts. Program so that have no wasted tool path. Limit z up to just clear the part. Set move and jog at max speed without sacrificing cut quality. I would suspect that you can do 700 in about a day and a half.

[srwtlc]

Gerald,

My material is red oak at 3/4" thick. I thought about cutting them out of boards, but the ovolo bit I want to use has a 1/2" diameter at the tip which would require a lot of waste. I can yeild better by ripping/crosscutting my blanks to 1/8" oversize and then having the Shopbot do the rest with the ovolo bit that can do the three cuts needed.

Ron,

I like the idea of the T-track. I've been thinking about something like that because I do so many different things and most are smaller items. My current table is starting to look like a pincushion. Is your T-track of aluminum, and do you have it flush or below the surface? Do you have some type of low profile clamps then?

I'm considering using two, what I would call palettes, that I can load up with as many as I can as close as I can with a template and then place them on the table at two different positions. That way I can be loading up one while one is being cut. And like John said, optimize the tool path.

Scott

[rgengrave@aol.com]

Scott send me an email and I will get some pictures for you, it will show you how you can use your whole table.
When you finish 1 peice just remove it while the rest is still cutting, then just add a new peice for when you run the file again.

I did 25,000 letters for Lowes last year doing it this way, it is a time saver and you will never mess up your table with screw holes

Ron V

[gerald_d]

Hi Ron V, I am also curious to see how you use "T-track" to hold a 5"x7" part so that the whole outer perimeter is clear for a cut right around the outer edge. My e-mail is mechtron@iafrica.com (mailto:mechtron@iafrica.com).

Scott, Have you considered the depth (z) control for the ovolo bit? If you want the radius to meet the top surface exactly (without a rebate mark) then it is essential to set the z dimension very accurately. On one of our jobs it was easier to do the ovolo work afterwards on a table router (the client-supplied blanks were of varying thickness). An ovolo with a ball-bearing on the nose works fine for this. The ShopBot doesn't automatically replace ALL traditional routers.

Theoretically, using a high vacuum (ejector or piston/vane pump) with a rubber inter-mask/seal will give you more than 300 pounds of clamp force. However, vacuum would only be considered as a very last resort - the special masks, seals and pumps tend to be very specific to a particular job and your 700 pieces still sounds a bit too low for such an investment/(experiment).

[gerald_d]

Thanks for the photos Ron V. I think you missed the fact that Scott wants to cut his blanks 1/8" oversize and do all the finishing in the ShopBot. In other words, he wants access to all the edges (the whole perimeter) right down to the full depth/thickness of the workpiece.

[swimsNOSPAM@mindspring.com]

I wouldn't discard the idea of a vacuum setup for this situation. I often use a Gast 3/4 horse pump with gasketed vacuum zones and/or templates. I cut and hold 4" diameter parts with a thickness of 0.40" in maple and cherry this way on a frequent and consistent basis. The only issue I would be concerned about is the 3/4" thickness and the number of passes to get a complete cut without the blank getting pushed around.

If the vacuum didn't look like it would work, or the number of passes were too time consuming, I would probably consider ganging up several parts per blank (larger blanks, of course), going with screws, and following John J's advise and setting up several different zones so that you can be removing and loading a set while another cuts.

It's also a good idea to prearrange a back rub from your significant other after a day of working like this.

[gerald_d]

One of the main factors in deciding how many parts to have on the table simultaneously, is the number of tool changes per job.

If you need say 3 different cutting tools to cut the part, then you probably want at least 10 parts on the table, so that you would do 210 tool changes for 700 parts.

The number of tool changes causes a lot of the back pain. This was another reason that we went to a table router for the ovolo work - one less tool change.

[srwtlc]

Great replies one and all, I've got my setup ready, tool path ready, and about 600 blanks cut. I had to order a different bit though as an ovolo bit with a 1/2" roundover won't cut to 3/4" deep without a stepped edge so I found a plunge point roundover bit from a local Whiteside dealer. I'll let you know how it goes.

Anyone else with a unique jig/holding setup for a special situation?

Scott

[rgengrave@aol.com]

Gerald if you flip the blocks and use the shallow end of it you can cut around any part.

Look at the picture I sent you and you will see what I mean.

Hummm I might not have sent you that Picture?

Ron V

[gerald_d]

Ron V, Scott wants to cut all the way down to the table in one go. Any form of clamping blocks (like you use for T-tables) would get in the way of this. His blanks are over-sized and I don't think that he wants to flip them over to finish off the edges from the back.

Also, if you are only going to press the L-blocks against the edges of the workpiece (from the x and y directions), so that the whole top surface of the workpiece is exposed, there will be no positive downward clamping pressure.

T-track tables are great because you can normally get 4 positive clamps on quick and easy. And for Scott's type of job, you could temporarily move the clamping blocks out of the way, one-by-one, as the tool comes past. Done that ourselves a couple of times. But we can also show some destroyed clamp blocks (and cutters) when the phone rang halfway through the job . . . . . .
&


Would you mind if I tried to put in links to your photos?

[gerald_d]

PS Ron V, wondering if you did try and send more photos in the last 8 hours? Only received two infected mails that Norton killed. But from the ashes left over in the quarantine box, they didn't come from any of your servers. If you do want to check your system, it was the BadTrans virus, again.

[rgengrave@aol.com]

I just flip the material and finish the cut, takes only a few seconds too do or I use use my router table I built to handle peices up to 4'x4'.

What the BadTrans back again...lol

Ron V

[srwtlc]

A belated update...We(wife, father, and myself)finished the 730 mug holders two weeks ago. The Bot earned its keep. I figure that it took approximatley 13 hours of just ShopBot time to shape the product. About a minute a piece, not including the time required to swap pallets, Dri-cote bit, etc. I ended up using a template to place an array of 24-5 1/8" x 7 1/8" red oak blanks on a 1/2" thick MDF pallet screwed down from the back. The pallet was then indexed on the table and the file ran whilst loading up another pallet. It took a few tries to get the best approach at a tool path that didn't splinter an edge off. I knew I would have to always back cut, and I came down from the top in two steps to start with, but the edge below the tip of the bit kept wanting to peel off no matter how I tried to come at it. I finally concluded that the plunge point tip of the bit was what was causing this problem, so I changed the path once more and came at them at full depth from the sides in two steps inward. Problem solved. The bit would come out and cut the circular pocket then do the sides with radiused corners and rounded over edges. I also clipped the corners of the blanks at a 45 on the miter saw first so the bit wouldn't work so hard on the radiuses. Three bit sharpenings later we had 730 pieces shaped. Now if there would have only been a way to turn a ShopBot into a profile sander. ;^) On to the next project.

[srwtlc]

Does anyone know of some suppliers of 1/4" diameter closed cell foam backer rod for vacuum clamping setups?

Scott

[edrawe]

HI Folks
My name is Ed and I am new here. I am really impressed with the willingness to share information among the users. I hope to own a PRT 96 soon. I have been reading a lot of the topics and this one is of great interest to me as it seems to be a keystone to sucessful cutting. I have not seen it mentioned but I was curious if anyone is using the type of two sided tape that turners use. I use it in the WW shop quite often and it will hold small pieces really well.
ED

[ezboy@microxl.com]

i have built two router tables from the ground up and starting on number three.
the information i have received from this form have solved a lot of problems before thy
had a chance to become a problem.
thanks.

[sheldon@dingwallguitars.com]

I'm not sure what type you are refering to, but I've had success with outdoor carpet tape (cloth type not the plastic type)and index pins for one-offs.

[gerald_d]

A Sci-Fi idea:

Why not build a big "electric blanket" into the table top and then use hot-melt adhesives?



Actually this is not new. Some cars are permanently fitted with a heating wire around the windscreen to melt the adhesive when the screen needs to be replaced.

[srwtlc]

Double-sided carpet tape (cloth type) does work well for holding material, but can be a bit messy to get it loose and cleaned up. I just got done doing a bunch of inlay where I used it to hold 1/8" walnut in place on a piece of 1/2" MDF that was then clamped down. After cutting was done I flooded the pieces with a bit of lacquer thinner.
It loosens it up fine, but boy what a sticky mess I had.

[shuttle]

I have used a dispenser which applies a strip of *just* adhesive. I have used it for cutting CD's, it is very strong and can be rubbed off after with the finger and pressure.

3M Scotch ATG High Performance Adhesive Transfer Tape 926

[allstarross@hotmail.com]

I'm considering buying a large shop bot for our sign shop. Does anyone have a fast easy way to hold down plex and aluminum for channel letters ect? I would love to see pictures of the t-track! Please send me anything that would help. It would be greatly appreciated. Feel free to e-mail me. Thanks, Ross Pettid

[edrawe]

The tape that I am talking about I get at WoodCraft Supply. It is no thicker that masking tape with adhesive on both sides. It is much stronger than carpet tape and not nearly as thick. It sells at WoodCraft for $11 a roll that is 1" wide. I believe woodturners use this alot.
If you use it on say 3/4 stock taped down to your workbench you will need to get some kind of tool under it to break it loose, very effective for free hand routing.
Ed

[Mayo]

A note to Scott about the tape and thinner...

I also use double sided cloth carpet tape. Normally I just try and twist the pieces free, or else I slip a 3" wide putty/spackle blade underneath and gradually lift. On thin parts it's risky.

The lacquer thinner idea seems like a good alternative to just prying the piece up, but it may be too strong a solvent and definately wouldn't work well on acrylic. I think if you try mineral spirits or xylol, it may produce less adhesive mess because they are less aggressive solvents.

One drawback would be that these solvents are more "oily" than lacquer thinner and would need to be cleaned off the table before trying to stick the next piece down. Maybe a final wipe down with lacquer thinner would be the solution.


Rob Shuttleworth: You cut CD's on the shopbot? I assume you mean you cut decorative shapes out of all the Free gazillion hours AOL CD's everyone gets in the mail? :-)

[zacman26]

more on solvents...

try using naptha, I use it to install grips on golf clubs it neturalizes the double sided tape and leaves no oily residue

[gerald_d]

This was posted on another thread in Novemeber - it might be worthwhile repeating here:

We have had a ShopBot for a year and we also had all these concerns about holding down the work in the beginning. Even purchased 2 different types of vacuum pump and had them ready to install in case a job came along for which vacuum clamping was essential. Well, that job hasn't come along yet!

There has almost always been a way to simply use two G-clamps and cut. BUT, the big trick is to know WHERE to start cutting.

An example is a recent job where we had to get 14 pizza platters, each nearly 18" diam, out of a 8'x4' sheet of marine ply. What we did was to draw the full sheet in a CAD program, and then started placing the platters (plus a 1/4" cut allowance) furthest away from the (0,0) corner. This left about a 6" wide strip along the left edge of the board (running in the y-direction).

Two G-clamps were placed, one at about (0,0) and the other at about (0,48) ie. the leftmost 2 corners. We knew from our CAD drawing that the cutter wouldn't come nearer than about 5" from the clamps (quite safe) and a strong, long off-cut would remain between the clamps for a strong anchor point.

Using a downward spiral cutter, to push the board gently down, we started to cut the first platter - the one furthest from the clamps. This is critical; it is like slicing bread - you must start furthest away from your holding/clamping hand so that the slices fall off one by one. Logical ain't it, and easy to remember.

But, the big trick is that for each individual platter (component) you must start the first plunge nearest to the clamps. In this example the cut is started at about the 9 o'clock position of each platter. The reason is that you want the platter to be attached to the firm clamp side during the last few seconds of the cut. And that really is all there is to it!


4787

Just think your cutting sequence through carefully as if you are slicing off bread slices and remember that each part must be firmly attached to the anchor side until the last moment. Don't cut little rectangular blanks from your boards and then try to hold the blanks down - use the whole board for clamping.

Okay, we have made a basic vacuum system, but we never rely on it for the clamping force. Our vacuum system is only to flatten down warped boards. Two G-clamps do all the holding-in-position work.

Using this starting-furthest-away method, you can keep track of half-used boards in the CAD system. It is very quick to throw a half-used or new board down at the (0,0) point, put on 2 clamps and start cutting.

In the beginning we were concentrating too hard to start the cutting at (0,0) and destroying our reference points and clamp strength in the process. Rather start far away and work back to (0,0)

[srwtlc]

Does anyone out there have a pattern or cutting file for a cam lever that could be used for repetitive wedging into place of numerous parts. One that could be screwed or bolted to the table where needed?

Thanks,

Scott

[rgbrown@itexas.net]

Scott,

There are about half a dozen styles of "cam clamps". If it will help, I can take pictures of at least three or four styles I have and send them to you. The most simple are very easy to make. The most complex I know are more involved than I would make in a simple wood shop.

Ron Brown - rgbrown@itexas.net (mailto:rgbrown@itexas.net)

If Stupidity got us into this mess,
then why can't it get us out? - Will Rogers

[srwtlc]

Ron,

What I'm looking for is a simple cam shaped lever that I can rotate into a corner block to wedge a group of parts in place. Somthing approx. 4". I know I've probably got some patterns in some old magazines, but finding those would take longer than a little trial and error. ;~)

Thanks

[sheldon@dingwallguitars.com]

Scott, I can email you a dxf of the simplest of cams. Drop me an email.

Ron, I'd like to see what you have. Could you email me a photo too? sheldon@dingwallguitars.com (mailto:sheldon@dingwallguitars.com)

Thanks.

[beacon14]

I make a simple cam quickly with the following method: Take a rectangular block, say 1 1/2" x 4 or 5 inches long. 3/4" thick hardwood works well. Set the table saw to run a kerf down the center of the block lenthwise, but only 1 /16" or so deep. Without moving the fence, turn the block 90 degrees and make another kerf, this kerf will be a crosscut, but still only 1/16" deep. Where the kerfs meet, use a compass to scribe a half-circle that just touches the end of the block, it should also just touch each edge of the block. (Put the point of the compass at the intersection of the kerfs.) Bandsaw and/or sand the end of the block to the half-circle.

Now here's the good part. With the block parallel to the workpiece or jig and about 1/16" away, screw the block to the table, placing the screw approx. 1/8" closer to the center of the block than the point where the kerfs meet. When you pivot the block around the screw, the end acts like a cam and moves 1/8" closer to the workpiece, making a nice tight fit.
Experiment with different size blocks; the larger the width, the more distance and force you can obtain. The position of the screw also makes a difference.

Even tho you don't get to make this on the shopbot (although you could), it takes only a minute to make and works well.

[shuttle]

The sawdust does a good job holding small parts in place when cuttting 3/4 plywood with a 1/4" bit that has flutes the same depth, the sawdust can't escape and is packed around the piece very tightly.

[gerald_d]

Rob, if the sawdust is packed that tightly into the cut, then your bit is doing extra work to re-cut the sawdust. The sawdust is then re-cycled into the bit. This causes a higher temperature and the bit to dull quicker.

[shuttle]

There were no signs of burning after 8 - 4" circles at 2 In/sec. with a Belins polished bit.

[Mayo]

I thought I would make some decorative pieces from the Pau Lope wood that I got, and I came up with something that has a celtic design engraved, and then the piece is cut out around the edge.

First I'm slicing the 2x10 wood into 1/4" thick blanks. From these blanks I can get 6 decorative pieces. I made a pocket in some scrap plywood, that holds the blank in position while it's being engraved. Now when I want to cut the individual pieces apart, the router bit destroys the shape of the pocket and makes it impossible to register the next piece.

I thought maybe if I cut through only half way, and then flipped the piece over and cut the other side, I would still have the bottom half of the pocket (which would now only be 1/8" high) to hold the piece in position while being engraved. The problem with this idea is that the design is not symmetrical and when I flip the blank over, it will not nest into the cut. I guess I could create a second pocket and have the cut out flipped so that it matches the turned over blank but I'm wondering if there's some more obvious or easy method of holding this.

The first image shows 6 round red holes which I was going to supply vacuum to from below. The pink rectangle is the pocket that the blank sits in. The blue decorative shapes represent the center line of the path that a 1/8" bit will follow to cut out each shape. The finished shapes measure about 1.375" x1.47"


4788

4789

[davidallen@iname.com]

you might try making the pocket larger than the blank and adding a sacrificial wedge between the blank and pocket. then when the outside is cut, the wedge is destroyed but the pocket is intact.

da

[gerald_d]

Mayo, we do this type of thing quite often in hardwood. Don't waste time by trying to flip the parts over. (Unless you also have decoration on the other side)

We would leave a tiny tabs between each part and the waste edges in your jig. In other words, 6 tabs along the top edge of the strip (in your diagram) and 6 tabs along the bottom edge. The tabs must be across the grain so that you can snap them afterwards. Also put the tab where you can sand off the rough spot easily with a belt sander. A 1/8" long tab seems to be sufficient.

Cut once, through full depth, break up, touch to a sander.

If you want me to show you the tabs, mail me your files.

[Mayo]

I had thought about the sacrificial wedge but I didn't have anything that was so thin... if I wedged each side so that it was centered, I would need wedges 1/16th thick. Not having anything like that laying around, I abandoned the idea.

Tabs... that sounds like a plan.
I'll try it on another jig set up and see how that works.

Thanks for the suggestions!

[garyb]

Mayo, I have done a number of projects similar to yours above and what I do is cut my blank 1/16" oversize in thickness, in your case to 5/16", do the engraving then cut out to 1/4" deep.
Run the blank through the surface planner to cut the pieces loose.

[gerald_d]

Gary, when the parts get as short as Mayo's 1.5", then they jam up in the planer's rollers and all hell can break loose. But this method does work great for longer parts that span the rollers properly.

[davidallen]

how about double sided tape? you could use a jig to locate and fix the board then remove the jig for reuse. the double sided tape should hold OK if you use the thicker cloth based tape, not paper based.

[miket]

I am new to this and have read a number of times that T-Track is a great way to hold parts down.
Can someone send me info and possibly pictures of T-track. Where can I buy it?

Thanks,
Mike

[rgbrown@itexas.net]

Mike a "GOOGLE" search for "T-Track" will bring up a lot of options and products.

My "New" table will have some t-track on it. It will have a lot of zoned Vacuum and stops.

Good luck,

Ron

[mdebruce]

Ron,
I am building a table for a PRT-96 and planned to use the plans on ShopBot's web site. I see ideas here that I would like to incorporate into my table. Do I need to modify the basic frame/table for any of these mods.? ie. T-Track, G-clamps, vacumn.
What style clamps do you find most useful
(any pics would be appreciated)

Newbie in Tennessee

[rgbrown@itexas.net]

Mark,

I am not the person to talk to about the "basic" table and the modifications needed to adapt anything to a "standard". I doubt if I ahve the "most modified" ShopBot but I would think mine would be called "highly unstandard".

I will contact you "off-line" and send some of my ideas in a few days.

[jimt]

Mark,

I have sucessfully used slatwall as a hold down "track" on my table for a couple years now. I used just the basic MDF variety, and shellacked it to keep it clean and pretty. I made some nuts from standard woodworking "T" nuts inserted in a piece of oak shaped to slide in the slots. You can't crank things down liek you would on a cast iron milling machine table, but it works fine for routing operations. Cheap, quick and easy!

[gerald_d]

I think that T-Track is too flexible unless it is attached to something strong about every 6 inches or less. Re-surfacing the table will also be a pain.

[rgbrown@itexas.net]

"I think that T-Track is too flexible unless it is attached to something strong about every 6 inches or less. Re-surfacing the table will also be a pain."

Yes, and a smart man would probably plan on trenching the "t-track" about 12mm low and then placing a shim under the track so it is only say - 3mm low. Then one could surface the table quite a few times before they had to overlay the table and start over. The cost of inserts so one could pull and replace the track without stripping out the screw-holes would need to be considered and how to keep vacuum leaks from effecting hold-down power needs to be thought of also.

The track I am looking at is 1" in depth and drilled ~ 150mm o/c. Is that more or less than 6"?

Ron

[gerald_d]

Is 1" about 25mm?


The most common T-Track channel (http://www.rockler.com/ecom7/favorites.cfm?sku=5325) I found on Google from USA suppliers is only around 1/2" deep and 3/4" wide. (The mighty (http://www.ttrackusa.com/track_%20systems.htm)"heavy-duty" one is not much bigger) Reckon that this small section should be fixed at 3" centers, or epoxied full length into a slot. If epoxied, then the alu should be grooved along the sides first - for the epoxy to key in.

(PS, this (http://www.harkenstore.com/uniface.urd/sccyspw1.eShowPage?409Z56LC7FV66&409Z56LC6OQJU) is not the T-Track that SB'ers are talking about)

[Mayo]

Anyone have experience cutting stacks of material, say 4 pieces 3/16 thick (total of 3/4") in one pass? If it works good, I'd save tons of time cutting an order for 3000 pieces out of Baltic Birch. Which style of bit? Spiral upcut or downcut?

[rgbrown@itexas.net]

Gerald,

I found an extrusion that is 22mm deep X 16mm wide and takes bolts with a 14mm head. The "American" 3/8 inch bolts will work and I can get nylon bolts and nuts.

Urethane adhesives would not require a "key" or one could get the aluminum to "bond" with the proper technique using epoxy.

I am a huge proponent of vacuum hold-down when practical and also use clamps, weights, shear-stops and drywall screws.

If someone wants to use dog-hair and bubblegum and it works for them - hey, have at it. Just like software, one should use what works for them. I have been told vacuum won't work South of the Equator. It has something to do with the metric system and brain-waves......

[gerald_d]

Ron, you mentioned shimming the track. Why not glue it down once only, deep down? And then save your cutting file for the T-Track grooves so that you can expose them again when you have laid a new spoilboard?

[rgbrown@itexas.net]

Gerald,

YOU are the one who wants to glue the tracks. I can't think of anything that would need that much force.

And, when one put new spoilboard on, if they had a "Northern hemisphere brain", they would be smart enough to not glue over the track.

I've got to stop knocking these African guys - I'll make a few typos and be up the creek....

I guess I want to register off the track in my mind and in reality know that won't work. I would use aluminum and plastic clamping bolts; nuts; and such,

[gerald_d]

Ron, I think it WOULD be smart to glue your spoilboard over the track - that would really anchor it very well. And it will be dead easy to open the 3/8" (or less grooves later) Try thinking outside the box sometimes.
Come to think of it now - putting a 3/4" thick spoilboard OVER the T-Tracks, and allowing that to sacrifice down to about 3/8" before replacing, would make a darn fine table. No?

The snag with a 3/8" bolt/screw is the fact that someone is going to come along one day and tighten them like the 3/8" bolts on his pickup truck . . . . . . . . If they are nylon bolts, that is fine

[rgbrown@itexas.net]

"The snag with a 3/8" bolt/screw is the fact that someone is going to come along one day and tighten them like the 3/8" bolts on his pickup truck . . . . . . . . If they are nylon bolts, that is fine"

I think I will be thankful I work by myself 99% of the time. And yes, I had thought about the ~ 8,000 pound force one could exert on each and every bolt on the track.

You may be right on gluing the spoil-board over the rail but, I am reluctant to agree for "manly" reasons. One of the other reasons is I hate to waste the track when I do a planned complete rebuild next year.

Thanks for the intelligent input. Working alone out in the "sticks" one tends to develop a single thought and doesn't have someone to tell you, "Hey, that's STUPID."

Ron

Metric is for those not smart enough to work in odd numbers.

[garyb]

Sorry Guys, but your making a simple process complicated.
I use "T" tack exclusively and don't have any problems, I screw the clamps down by feel, sometimes till the track bows up between the attachment screws but it will just pop back down once released.

On my steel table, I surfaced the 2x4's then installed 1 sheet of 3/4 "MDX". I surfaced the MDX then cut 3/4 dadoes to a depth of 1/8 to recess the "T" track in the MDX board.
The "T" track I have has screw holes every 12" but I did add some additional in the heavy use area of my table.

Once I installed the "T" track I then ripped 1/2" ply for the spoil board. This is cut tight between the track and is 1/8 above the track.

I now just change out the 5" strips of spoil board as needed. Simple, easy, and has worked great for 2 years.

[pcampbell86@charter.net]

Hi all

Hey gary can you post Photographs of your hold down system...as it sounds like the one for me
also the types of clamps etc..could you show a piece of work on the table?

thanks

Paul

[garyb]

Paul
I will take some photos and email them to you this weekend.
The track I use is 3/4" X 3/4" X 48 then for clamps etc I purchased bags of "T" bolts, knobs and some lever locks. I don't recall where I purchased these items at but most are available in your regular catalogues like Rocker etc.
gary

[kerrazy]

gary I would like a copy of those photos if I could please.

Dale

[fitz943]

Why not make a t-track out of plywood/mdf? Take a flat top of plywood, cut plywood strips 4" wide by the length of the table, space them 2" apart and attach to top. Then cut mdf 5.5" wide by the length of the table and attach them over the 4" strips forming a t-slot .5" wide with a slot 2" wide by .75" tall for a nut? You would need to pay for 3 sheets of wood, but that has got to be cheaper than buying aluminum t-track to cover the whole table.