Workbench / sawbench project

[Argonaut]

Decided to build a sturdy workbench, specifically to take my chop saw and saw table.
The saw table often fails to get used as it is so difficult with large materials ….trestle supports often topple. By having a decent width of table and a long outfeed support of the bench top … should make things a lot easier.
Basic shape is similar to : http://tinyurl.com/k556y8z

The top will be 2 sheets of ¾” MDF. I’ll edge it with some hardwood (1/2” thick or similar) to prevent MDF damage.
Frame is built and finished size is 91” x 41” …. I used 4x2 for the rails and for the ‘legs’ used a 6x2” and 4x2” joined in an L shape with biscuit jointing.
Invested in a KREG pocket hole jig (HD variant) for fixing all the 4x2” together – impressed with that jointing method – really pulls joints together.

In the link given it shows the top as flush with support frame … wondering whether it might be better to have it overhang a bit … make it easier for clamping.
I did see one design on line that showed a 5” overhang …. http://tinyurl.com/lkcrd2w
That might be too much .. maybe 2” overhang is enough.
Anybody built a similar bench – any thoughts?

Also on fitting the top …. Think the approach is screw down first sheet with csk screws into frame …. Sturdy fixing. The glue 2nd sheet to first with PVA. Avoids any screws in the top.
Unless anybody sees flawed logic on this.

 

[williams1185]

just a thought if you damage the top sheet how would you replace it ? why not screw the two sheets down and pin a replaceable thin board on top .ian

 

[JWD]

Further to ian's point, id use two sheets but only hold the top one down with 3 or 4 screws, make it dead easy to replace? If you do this dont forget that you dont want to attach the edging to the top sheet.

My bench is a solid mahogany door with MDF on top, edged with keruing (i think) which is very strong and durable. Suits me a treat

Joe

 

[Argonaut]

So maybe screw down first sheet .... drill a a load of clearance holes ... then put 2nd sheet on top ... screw through lower sheet up into top sheet ... clearance holes will allow wood to be puled tight by screws.
Edge with hardwood but only glue it to lower sheet ... could apply a run of selotape to edge of top sheet to act as bond breaker.

Read a few reports of treating top sheet with 2 coats of boiled linseed oil, then 2 wipe coats of polyurethane on top .... I would never have thought of putting polyurethane on top of oiled surface ... but seems common in some wood working forums.

 

[Neil S]

+1 for using 2 sheets as stated but add a final top sheet of hardboard that is very durable and also quick and cheap to replace.
Edit: If you made the edging high enough so the hard board sat in it flush you might not even need to fix it down. But if you need to you could probably stick just the corners down with double sided carpet tape.
The only time this might not work is of you wanted to include dog holes for hold fasts. But then hold fasts might not work so well with MDF anyway.

Neil

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[Argonaut]

Interesting thought on hardboard - had not considered that.

Don't intend using hold-fasts

 

[gmgmgm]

My workbench has a few 18mm MDF boards resting on each other. Probably 5 or 6 layers. They're held together with 2 clamps, and don't budge an inch. You can probably pin them in place with a couple of long countersunk screws, rather than gluing them all in. Then when one starts to get tired, either turn it over, or throw it away and use the next layer down.

I've finished the top with Osmo/danish whenever I've had a brush I wanted to dry off. Probably not necessary to use PU as well.