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Thread: Fence Mounted Push Block
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15th October 2013, 11:20 AM #1SENIOR MEMBER
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Fence Mounted Push Block
Hi all,
I am nearing the completion of restoring my Stenner ABM 18" Patternmakers saw https://www.woodworkforums.com/f163/s...ration-157563/, so it's time to start thinking of accessories. I have decided I will try to add a push block to mount semi permanently to the fence for ripping cuts.
The other day was extremely hot (too hot for the workshop), so I decided to build one on the computer first, get an idea of what I want before I start wasting material.
This is a picture of the saw and fence, so you can get an idea of what I am talking about in the sketchup images:
front.jpgback.jpgStenner side.jpgStenner front right.jpg
The design in the sketchup is not quite correct, as I neglected to check the fence and thought the fence sat above the fence support, so I will need to extend the top of the fence (I can use the dovetails in the back of the fence to secure the extra piece for the push block to ride on).
These are the sketchup images, (not to scale, just a representation of the basic concept).
image 2.jpgimage 3.jpgimage 1.jpg
This is not an original design, by any means (so I am thinking in practice everything should be fine), the basic idea is that the push block will ride the top of the fence, the front pressure stick is adjustable to the height of the stock being ripped and then locked into place, the back piece is allowed to pivot forward so the stock can move past the block, and then once the workpiece has moved past the back of the push block the back stick drops down and is prevented from moving backwards and as such can advance the end of the workpiece through the cut.
I had thought about making the front hold down, into antikickback claws, but this saw has a short fence and riving knife, so I figured this was less of an issue. My main concern in practice may be how far forward the push block can be supported with the short fence (as most designs I have seen generally are being used on a biesemeyer style fence), but I guess if I had to, I could extend the top extension that I will be adding, past the end of the fence.
I have used push blocks and sticks before, so I am used to the concept (pressure of cause will be applied to hold the work piece against the fence either manually or using a featherboard arrangement), but I have never used a push block that rides the fence, so I thought as I already had it made digitally, I should share it with you guys for comments, recommendations.
Cheers,
Camo
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15th October 2013 11:20 AM # ADSGoogle Adsense Advertisement
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15th October 2013, 01:10 PM #2
I've been meaning to make something similar, especially for narrow rips. I like the idea of the front hold down. I will pinch that bit and modify it slightly by adding fingers to maintain the downward pressure. The swing up rear pusher is a good idea too. OK, consider the whole thing pinched. (just thinking out loud here-would need to be able to lock it to the fence initially and then easily release as the workpiece moved past, cam action maybe.)
Those were the droids I was looking for.
https://autoblastgates.com.au
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15th October 2013, 06:30 PM #3SENIOR MEMBER
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Pinch away, it's all been pinched before by me.
I see what you mean by the locking (to prevent the block feeding with the workpiece), I thought last night about the fact that I need some movement at the front to actually apply downward pressure at the front when pressure is applied to the handle, I did not intend the front piece to actively apply pressure until I started applying pressure to the handle. I thought it might need a spring at the front to lift the push block slightly until I grab and hold down the handle, this way I can adjust the front hold down so that it is applying actual pressure once the spring is compressed (I hope that makes sense). A featherboard that holds the stock down the full time, would not work with my design as it simply straddles the fence and is not held down by anything other than the person, when the handle is grabbed.
If you were to go with the featherboard and hence wanted to hold the stock down when you don't have your hand on the handle, then it would like you say need to be locked into position and some form of quick release like a cam is required. It would also need to run on some form of rail, so that the downward pressure could be maintained when you are not holding the handle. I guess you may also need to release the pressure that the featherboard is applying (if you are ripping several pieces and have an outfeed table), otherwise pulling the push block back may also result in pulling the workpiece back. One solution with that might be to ride the push block on a track like in this picture below.
ramp.jpg
Effectively, it has a ramp at the end designed to remove the pressure of the featherboard enough so that when you start pulling the push block back, it doesn't want to take the workpiece back with it (I doubt it would take much of a rise, just enough to be certain it wouldn't hold on).
I can see how this could become a really complex addition if you wanted it to be.
Cheers,
Camo
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