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Edge Finder

Tony Spear has reminded me that this gadget is not suitable for the Little Rat.

I have received a number of emails asking, in essence, if I have a way of setting the router bit cutting edge in alignment with the edge of the work-piece before plunging. Well, I do not normally have too much of a problem with gently sliding the router plate until the cutter just comes into contact with the work, but after some experimentation have come up with this little gadget.

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Its 1/4" (6mm) thick acrylic plastic and 5" long. It is rebated along both long edges so that it is a smooth sliding fit in the router plate just like the centre finder.

 

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Underneath is glued a 1" by 1/2" projecting tongue as shown in the photo. I used super glue which works very well on the plastic.

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Cut a 1/8" deep by 1" wide trench, the rear edge of which must be in vertical alignment with the front edge of the vertical tongue. This leaves a horizontal strip (covered in black tape for visibility and protection) which is exactly the same depth as the tongue.
border="0"  This drawing shows how to set any diameter cutter to align with either the front or rear edge of the work before plunging.
border="0" This drawing shows how to set the cutter to exactly form a rebate at the cutter diameter from the edges of the work. Left click to enlarge.

With the work cammed and in position under the router plate, slide the finder until the tongue is in contact with the relevant edge. Hold in position and slide the router plate until you have aligned the cutter edge as described below. Lock the router plate, slide back the edge finder and plunge the router with the power off just to double check your positioning.

To set the position I have found it best (with the power off!!!) to manually rotate the cutter in reverse and slide the finder until the cutting edge just "kisses" the acrylic.


Centre Scribe

Here are some pictures of a third little gadget created whilst "playing with the plastic" It complements the edge and centre finders and makes life with the Woodrat just that little bit easier.

The concept of this aid is not new, variations having been in use for years, however my version is quick to make and different from the norm. Take a look and see what you think.

The purpose of this aid is to either mark a line down the the centre of the edge of a board or to just simply mark a centre spot.

The sizes are all arbitrary and the pictures just demonstrate the method of construction.

I cut a piece of 6mm clear acrylic 3.5 inches by 1 inch and carefully marked the centre of the strip.

With dividers I lightly scribed an arc of 1.25" radius from the centre mark. border="0"

I found a small masonry nail, (one with a smooth shank and even conical point), measured its diameter and drilled a hole through the plastic at the marked centre. Arrange that the nail is a smooth but not loose fit in the hole. I used a drill press to be certain that the hole was at 90 degrees to the face of the plastic. A masonry nail was used because they are very hard and the point will not easily become blunt.

Now the part that needs care. On the scribed arcs, drill and tap two holes to take some short stainless steel allen bolts. The bolt holes must be equidistant from the centre nail hole and lie along a straight line. This is important!! I used stainless 6mm  allen bolts because they have very smooth, fairly deep, circular and accurately machined heads.

 Screw the bolts up into the plastic, (they do not have to be tight) and slide the nail down from the upper face as shown here   border="0" OK, polish up the plastic edges to make it look nice and its ready to use.

  border="0" Clamp the work on edge and lay the scribe onto the wood as shown here. Rotate until both bolt heads are in contact with the work faces and slide along. The nail only needs to be very slightly projecting to leave a scribed line down the centre. In the photo ,for the sake of clarity, I have been very heavy handed and marked  a groove.  This works for any thickness of wood up to the distance apart of the bolts. Make a bigger one for thicker timber.

The advantage of using acrylic is that you have a wide bearing surface and that being transparent you can exactly scribe between two set points without marking what will be visible wood.

You could of course use a propelling pencil instead of nail to mark the line.  

  border="0" Place on the board edge, rotate until the bolts are in contact and give the nail a tap to centre pop a mark.

Use this tool in conjunction with the centre finder to rout out exactly centred mortises.

Note: If you do happen to make this gadget with the bolts not exactly equidistant from the centre, it can still be used. Run it along the edge, leaving a mark, lift and replace at the opposing angle and again run it along the edge. This will leave two parallel lines that are very close together. The true centre will be the mid point between these lines.


Play Eliminator (mk1)

Pontop in the Woodrat Forum has recently posted some pictures of his excellent idea for a gadget to reduce "rattle" in the sliding carriage. I made one but did find it quite sensitive to adjust so that the carriage would slide freely whilst still reducing play so using his design principles came up with my own low friction version.

 

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Yes, I have used 6mm acrylic plastic again!

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Instead of wood I have used a strip of 1" by 4 1/4" by 6mm acrylic like this .     

A 1 and 1/4 inch strip of self adhesive very low friction tape was stuck on either end.  6mm plastic seems to give exactly the right 'spring' tension when fitted. The bolt clearance hole is drilled in the centre of the strip.

 

 Cut a one inch wide piece of 6mm plastic and rebate it to be a good sliding fit in the carriage. You can take the measurements from the cam-lock mounting. I purchased a 5mm coach bolt for a few pence. This type has a very shallow but wide domed head with a small square section on the shank below the head and so is self captive when fixed. Drill a 5mm hole into the centre of the plastic and carefully file the hole square so that the bolt fits flush and cannot rotate, like this:   

 

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I filed the head flatter to ensure that it clears the ratchet teeth.          

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I drilled a one inch by one and a half inch piece of brass and bent it to act as a combined washer and anti-rotation plate. Steel or alloy would do just as well. I didn't have a suitable knob available so I used a 5mm threaded piece of brass that I made for a previous experiment. 

When fitted to the carriage it looks like this.    border="0"

Should normally be set beside a fence like Pontop's photo but can easily be slid and fixed at any position.

Because there is a gap between the front and rear plastic pieces, tightening the knob bends the long top piece and so it acts and  as a tensioning spring, therefore pulling the carriage forward and flush with the channel. Play is automatically removed. The low friction strips mean that however tight the knob is turned, the carriage still travels very smoothly. The brass strip prevents the long plastic piece from rotating when the carriage is moved. The screw tension is not sensitive.

 

 I plan to curve diagonal corners of the smaller plastic piece so that it can be inserted at any position on the carriage without with the need to remove and refit a fence and also to test how narrow it can be made to maximise the working width between the fence and cam-lock.

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Although it does not appear to be in the 2004 catalogue,  Axminster Power Tools assure me they have this Slick Tape in stock. It comes in 36x3inchx1mm lengths. Part number APTCST3 and costs £4.37 plus delivery a box. It is for fences, router tables etc. and can be "cut to desired size by using Utility Knife or Scissors. Then peel off strips and apply to clean dry surface area." Very slippery and useful stuff!

 


Trend Clamp

I was tidying up the workshop and dusting off my Trend back to back clamp/straight edge when I was hit by a flash of inspiration, (hey I wonder if I could use this on the 'Rat?) and so had to dash off to get the camera. What you see here are the first thoughts of a very quick and easy way to hold small pieces on the Woodrat and really lends itself, I think, for some further development. Take a look and see what you can come up with!

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This is my elderly Trend clamp. They come in different sizes.

Axminster Power tools are now selling an improved version of their own called ProGrip Clamp Guides The 24"version currently costs£24.90 inc VAT plus£10.90 inc VAT for the back to back adaptor kit    

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To prove the idea I used my small work holding jig to mount the Trend clamp on. Its the mounting arrangement that needs improving.

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The Trend clamped onto the Jig

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The work fixed to the clamp.

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Very small pieces can be quickly fixed with just the rotation of the lever on the end of the clamp and tracked under the router plate.

 I am already thinking of various way of using this clamp both horizontally and vertically. Why don't you post your ideas onto the Woodrat forum?


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