Wednesday, 1 December 2010

plywood sheet support jig .

I felt one of these were necessary as moving 18mm sheeting about ready to cut on your own can be very difficult, and at times dangerous, I wanted this jig to give that bit of extra support whilst manoeuvring the sheet material for clamping with the two toggle hold downs and to help keep it balanced while doing this, like an extra pair of hands really, extra support till you pass the point of balance on the leading edge of the plywood till your table saw takes all the weight of the sheet being fed through the cut.

I have previously used the roller type free standing material supports but these tend to steer the materials where you don’t want it to go, hate that.

I wanted this jig to be permanently attached to the saw main body and easily accessible with ease of assemble which would only take seconds to do , not minuets, and not get in my way when in or out of use. This meant that no shop bought one would be any good to me so set about designing my own design.

I had left over from my Triton ETA300 sliding carriage a support leg with its balance foot which is 30mm steel square tubing , I decided to use this with one rollerball I also had left over from my turntable thread.

For this thread I decided I wanted to use as much bits and bobs around the workshop as I could, (recycle) so I came up with this idea.

This gave me my first problem to solve how to fit a round peg into a square hole. Square tubing, with a round roller ball attached.

Here I use a short 100mm piece of ordinal sink waste 1/1/2” PVC which has enough elasticity to be tapped on to the 30mm square tubing easily and it is a very tight fit, when on the roller ball fits snugly into the other end, both ends will be glued using araldite later. 

Now I had to come up with how do I keep it out of my way when not it use and easily accessible, and it had to be assembled/disassemble very quickly. I eventually decided sliding bar and fold up/down arm, with roller ball attached.

The support leg I had with bracket had to be altered as I could see no point in having a length of square tubing stuck out which has no purpose. As seen here before and after.

Now to work on how to  attach it up under the saw beds, remember I want it permanently attached.

O n my saw I have already  attached two extra side bed extension leafs, one either side, the one on the right to give extra support  primarily  for cutting  8*4 sheets in half across the sheet,  this also applies to the one on the left , but the left one will also house a router station as well as the sliding carriage attached on again for cross cutting purposes.

When the sliding carriage is set up, a full sheet  when let go of  will tip backward,  as there is not enough of the sheet from the saws front cutting edge to the front edge of the table on the right  of the blade to keep the sheet balanced, this is where this sliding  extending arm come in.

Luckily for me the extension bed comes with pre drilled hole to bolt  straight to the original saw bed, so from here underneath this is where I will   bolt on the housing for the sliding extension bar.

Again using bits & bobs from around the workshop I cut  a piece of  MDF:-

1) 800mm * 300mm * 25mm. HOUSING BACK PLATE

2. 800MM *30mm * 25mm  European  oak HOUSING RUNNERS

1). 800mm * 80mm * 80mm *25mm MDF HOUSING  FRONT PLATE.

 As seen here.

As can be seen  in the photo on the right the arm is now  extended and locked  with the vertical arm in the raised position, I must point out here  until I have the back plate mounted under the saw beds the raised arm cannot be cut down in length.  which has to be able to fold down as well as being raised  this is why I cut the back mounting plate at 300mm deep  just in case I need to adjust it up or down to allow the arm to swing equally in both directions, so the arm when lowered does not  hit the floor.

Now the locking devise is simple a furniture locking nut  with an 8mm bolt and turn handle as shown.

As I was building the housing box I realised I will need some metal plating screwed to the face side of the   backing  MDF plate with a hole pre  drilled  through  it,  as the hole is  quite  close to the edge of  the MDF to rely solely on the MDF strength, so this is where I had to stop for the day as I need to pop into town tomorrow to get some metal  plating to do this .

To fix the sliding arm box underneath I simple used flat bar  screwed to the face of the MDF,  with one hole drill through it, I then removed the two end bolts that bolt the extension bed to the  table saw bed  replaced the bolt with longer one and bolted it  on.

 These photos showing  position, extended and raised , closed and tucked away.  and it now full height cut to length.

The final photo  showing it all set up ready, unfortunately I don't have a full sheet to demonstate it  better but  I think you'll get the idea .

I place a piece of MDF  in front  of and to the right  of  the blade flush with the sliding fence the far end represent the end of an  8' sheet  . the sliding stop  adjuster is set to 4' to the left of the blade  this giving you  the  full length of the sheet  to be cut in two equal halfs.

To see the width of the sheet better I placed  a rule  in the photo where it rest on the  rubber support from the sliding carriage it measure approximately 30" now with the slid out  bar fitted on the right of the saw table bed, Now slide it out in  line, raise the arm and locked it, Now I  have the full length of the sheet  supported and  balance evenly down it's length so it wont tip  backwards  whist I  manoeuvring  it into position to lock the  hold down handle  before cutting.

Now where that  araldite, I'm fed up chasing that bloody  roller ball around the workshop.


PS  Remember  you seen it here in theworkshop  first.

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