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Review16 Page 2 MortiseTable Work Holding
I have been working away and experimenting on simple work holding methods for the Mortise Table (actually in table mode). There are numerous ways to hold your work but I wanted a simple, low profile and quick fit/release design. There is of course the snail cam path but wanted to to progress beyond that if I could.
I have come up with a Cam Paddle design and simple positioning /locking collars that securely hold your work and is also low profile.
Please let me know what you think.
|There are two parts to this idea. The first being the collars and
the second the cam paddle. I made up a set of collars as shown opposite.
If you have a lathe it makes for an easy life but it is not required. I
used some metric oval T-slot nuts which are included in the Router Boss
kit and cut some half inch long metal collars like this. The wider
ones are in brass and the smaller diameter ones are in stainless steel.
The material is not that important and plastic or even hardwood will
work. A hole is bored through the centre of each to suit the diameter of
the securing Allen bolts. The bolt with the washer does not pass through
a collar and is used as a fulcrum or pivot bolt. I selected stainless
ones as they are stiffer and harder wearing.
Note: I filed up a couple of alloy parts to match the table T-slots. More on that later.
|Perhaps not the clearest photos but this is just one cam paddle. The handle part is not critical in shape but the bulbous end is derived from a snail cam shape shown below the paddle. I made use of a French curves template to draw it up. Three slots to suite the Allen bolt diameter are cut in the end of the paddle.|
|Here it is in use. The work is prevented from moving East/West by
sliding up as many collars as needed. The pivot bolt is placed in a slot
and the paddle engaged as shown. The various paddle slots are required
as work width and T slot positions are variable. Turn the paddle
allowing the engaging edge to sort of 'roll' along the work so there is
not frictional damage. ( The pivot bolt may slide a little).
Lock the paddle in engagement with another collar and nothing can move at all. Just lightly pinch down the pivot bolt. It is best to position the paddle to hold the work centrally and take care not to place too high a locking force as there is considerable mechanical advantage with this sytem.
|Now originally I just used the oval T slot nuts for the pivot bolt but there can be a high sideways force on it and it is really designed for a vertical tension. I therefore filed up some alloy inserts that are a full fit in the T slots to better cope with the levering load. Don't make them too tight a depth fit in the T slot or they won't pass over the angle bracket bolt ends that very slightly project into the T slot bottom.|
|Having a choice of collar diameters gives more flexibility when locking the paddle when only a smaller area of T slot is exposed.|
|Occasionally a packer may be needed behind the work to bring it into the best locking position on the table. It is fortunate that the T slot are not equally spaced on the table so there is a great deal of flexibility in fixing. Do not be afraid to use extra collars as they are extremely quick and easy to fit.|
|If the paddle does not fit too well one way around just flip it over and use the smaller snail cam profile on the other side as shown here. It works just as well.|
|Holding irregular shaped work is so easy with these collars!
When finished working on the part loosen the paddle lock collar and slide back. The paddle pulls away and the work released in seconds. Just remember not to place collars where there is a danger of running into them with the router bit.
If you want to rout a slot right through the work then pack it up on some MDF etc. which is smaller than the work. The paddle and collars still hold it in position.
The paddle will work to the right or to the left.
|Remember Lewis mentioned that the table what not intended to hold work at the pre defined angles? Well here you can. I have used the plastic pegs to set the angle and added extra positioning collars around the work to prevent it moving in any direction. The paddle is set and ready for it's locking collar to be inserted before working on it. CHECK everything is well secured BEFORE routing.|
|Just another view showing how easy it is to hold strangely shaped work.|
|The paddle is simple to knock out from say 12 mm MDF and works well
but I have made one from 6 mm acrylic for thinner more delicate work.
The brown Tufnell one being held is my Mark One version which is OK but not so versatile. When I have some more time I will fashion a snail type from Tufnell which is, well.... darn tough!
|MDF and Acrylic side by side.
What's that? Why didn't I drill a hole through the paddle like the original snail cam?
Well I did but but in my experiments I could not get it to work well with friction between the work and the cam plus finding the optimum pivot point on the table took more time. It proved not to be quick fit/release either.
You could of course make a range of paddle sizes and thickness.
Well there we are, just one of many ways to hold your work on the Craftsman Gallery Mortise Table.
For a very small donation towards the site expenses I will email you a paper template of my paddle in PDF format.
Email me here
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