Thread: WIP: "Insane Lapping" or "RSG's Aerobic Workout"

After a bit more work the jointer outfeed table is flat at 40 grit.

Unfortunately I need a bigger piece of glass to be able to do the infeed table due to the extra width of the bit that the guard is mounted on. So I'm now considering getting a piece big enough to work both tables at the same time and doing it properly.

Even at 40 grit the table feels smooth and usable but once everything is flattened I'll probably keep working on them just for aesthetics. The scratches that I've left aren't as deep as the grind marks it had originally so it can't be too bad.

I've also done a very rough map of the bandsaw table (which hasn't had much more work done to it) just to show what sort of bowl I'm dealing with. I admit that the bandsaw table probably doesn't need to be super flat, unlike the jointer, but the dip was visible to the naked eye and it was one of those niggling little things that I hated looking at. It can't hurt to make it better anyway

Can you show and tell us what's underneath the sandpaper?

Looks like another container shed
Redshirt guy
I'm watching this one with interest

Originally Posted by BobL

Can you show and tell us what's underneath the sandpaper?

It's a 16mm MDF board (couldn't get 18mm at the time ) with a sheet of glass (700 x 450) from an old coffee table glued to it with Weldbond. Atm I'm using a 10mt roll of cruddy yellow 40 grit sandpaper, which goes blunt very quickly, and sticking the four pieces down as close to edge to edge as I can with a spray contact adhesive and using a roller to ensure it's stuck down flat. Then I flip it over onto my workbench (which *is* flat) to dry for a while as you don't want any little edges to lift up because it will muck everything up.

Because the sandpaper isn't one single piece I've been using a mostly large circular action, and rotating the piece I'm working on (while always keeping it within the boundaries of the sandpaper), so if the joins in the sandpaper are uneven, I don't get an uneven finish on the work piece. When I get up to 80 grit I'll use sheets of wet and dry instead of rolls and that will also change the action I use (piccies later).

I've been thinking today that at these low grits the glass plate might be overkill and instead of buying a piece of glass and MDF just for this one off job I should be able to get away with a bit of laminated chipboard with a frame on the back (only glued so it keeps the working face flat and clear of screws and holes) to stop any potential sagging, as to do both jointer tables at once (mounted on the machine) I'll be looking at about a 2mt long board for tables that are, together, 1.2m long (it's only a wee 6" jointer).

The glass/laminate makes it easy to clean off the adhesive residue with turps when I change sandpaper.


I'm not really basing this process off anything (other than how I sharpen my blades/chisels)...it's just something I'm doing off my own back with little to no research. It really couldn't make anything worse and the progress so far has been quite pleasing.

When I've been measuring, I've used a 36" Veritas steel straight edge (accurate to within .0015") and feeler gauges.

I did go to a few local engineering firms but none of them had surface grinders large enough to do the work...so I've got no idea how cost effective it is with my method either.


Hopefully when all is said and done I'll be able to say "yes, this works quite well for about $XX" if anyone else is mad enough to have a go.

Originally Posted by Simplicity

Looks like another container shed

Otherwise known as "The Summer Death Box"

I know the summer death box
Also the winter chill bin
We are building a home out of them right now.
We tend to leave the fridge open during winter to warm the ace up lol.
I think your approach to flatting the beds is properly about the same one I would take. exception being I would want to try and get some 32mm mdf laminate on some aluminum sheet then stick down the sandpaper.

Aahahaha, I love the fridge line because I know exactly how that feels too. At least in winter I'm not dropping sweat and staining everything I'm working on

I wish I took some photos from a job a couple of years ago because I saw some incredibly well done up number of containers as weekenders for out bush. They'd put in windows, attached a verandah and patio, and had a few of them out there for big family weekends/holidays including one for storage of motorbikes and a generator etc. I'm almost tempted to tear down the POS shed on my bush block and replace it with a container, but you can't beat a 6x9mt space to have a bunch of mates come out, no matter how shoddily it was built.


Aaaaaaanyway, I took the plunge to at least test my chipboard theory and have started very carefully gluing a frame onto the underside...one piece at a time, and clamped against straight edges (a couple of spirit levels) to ensure they're pretty much flat. I won't know for a few days how well this will work but I'll post some piccies later even if it's a complete fail.

The thicker MDF is a good idea. I do have a massive sheet of it, but it's old and warped so I'm seeing what I can do with new/cheap stuff ($18 for the piece I'm using) for a once off.

I tried to map out the surface of the infeed table of the jointer tonight but it's all over the place and was a nightmare to translate graphically. *Generally* it's only ever .05mm out in most directions (with a "pit" in the middle). However, if I include the bit protruding out the side where the blade guard gets mounted it jumps up to +.25mm. So what I think I'll do is belt sand that "platform" down so that it's out of the way (seeing as technically timber will never pass over it) and then hopefully have an easier time with the rest of the sanding.

*IF* this chipboard idea works satisfactorily, the only problem I think I'll have is from having done one table by itself. It'll be a bit of fiddling to level one untouched table to the other without doubling up on the work load, but I'll just have to see how it goes.

So far I'm thinking that a few .05mm deep spots isn't too bad at all and technically the jointer should perform better than it ever has. It really was all over the place, even after painstakingly shimming the outfeed table. It was a while ago, but I recall not being able to get it close enough to coplanar to consider it workable at more than a weekend warrior level (which is no insult...just comparing backyard apples to factory oranges).


Some more in a few days...

I have to say you are very keen! Well done so far.
I'd like to make a few comments from a metal worker's perspective if I may.
Many woodworkers think that a cast iron table is rigid, but that is surprisingly not the case. You can see that for yourself on the bandsaw table you show here:
Without the pin or grub screw in the saw blade slot, just press with your hand on the two sides of the slot in opposite directions. You may be surprised how little force it takes to flex that lump of cast iron by a millimeter or two. Whenever I do that to show woodworkers, their eyes pop out... that's why you should keep the pin or grub screw in the hole in the end to prevent that when you put a heavy piece of timber on the saw.
Taking the tables off their machine mountings is fraught with risk - i.e. they change shape and what you measure on the bench may not be a real representation of the flatness on the machine. FOr that reason it is generalyy better to work 'upside down' form your way of working. In other words, do the measuring and lapping ON THE machine, moving your piece of glass with attached sandpaper facing down on the machine (wherever you can).
Also, a thick sheet of glass will be cast glass tha has been polished flat. THe function is to make it optically clear, NOT flat. It really is the wrong tool for this purpose, I'm afraid.
You would get much better results with a smallish granite surface plate. They cost from around $65 at CarbaTec. These are certified to within a few microns (0.001mm) across their entire surface and will give you real flatness.
The last comment is that you will be working very hard to remove the 0.3mm high area form your band saw table. That is a lot of cast iron to shift. A surface grinder, planer or large milling machine or shaper is the way to go there. You can always improve on the flatness and surface finish of a planer, mill or shaper, but at least you will take the bult of the material off. A surface grinder will make it flat to within a few microns and you are unlikely to improve on that with sand paper - nor would you need to of course.
Metalworkers who restore machine tools - as many of us on this forum here do - level surfaces by hand scraping (or a few of us with dedicated electric metal scrapers) and we achieve flatness as good as a surface grinder. But I hate scraping anything more than 2 or 3 thou (0.05mm or 0.075mm) to start with on larger surfaces. We use blueing on a granite or cast iron surface plate to check the progress, flatness and distribution of 'high' spots....
Wherabouts are you ('rat? - Balla or Ara? or somewhere else?)? There may be forum member with suitably sized surface grinders who would help you!
Mine isn't big enough either I'm afraid....and neither is my mill or shaper

Good luck and keep us informed about what you find and your progress.

Thanks Joe.

In the past I learned (the hard way) that solid metal can flex so I'm right with you on that one. I've kept the pin in the bandsaw table to try to help keep the split level. I'll be done with the table when I've got most of the area to the left of the mitre slot and around the blade reasonably flat. I wouldn't class a bandsaw (well, not this one) as a precision machine so near enough is going to be good enough and still a huge improvement from what it was. As long as it doesn't make workpieces dip and flex while cutting I'll be happy.

Again I'm with you on the "upside down" working. I probably went to far with the jointer table but will now be working with both tables mounted and tensioned properly with the sandpaper facing down. I wouldn't be surprised to find that I will still need to shim one of them when I'm done with the sanding...although I'm hoping I won't...the ol' dovetail slides can be a bit fussy if they're moved too much or tensioned differently.

I had wondered if scraping would help out on the bandsaw table but haven't bothered to look into it. For the moment, while I've got a bit of wiggle room, I'm giving the already flat bits of the table, just on the edges, a light swipe or two with a belt sander to roughly bring them down before going back to the sanding plate to see how much closer it got me. It saves a bit of elbow grease as well as "wasted" sandpaper getting everything closer than .3mm across the area.

I'm in Ballarat (I really should fix that in my profile). It was interesting seeing some of the machinery from the local engineering firms and the limitations of them especially for this kind of work. I'd be tremendously surprised if someone local had bigger gear in their back shed. This has been an interesting process and despite the slow pace and effort required it has been somewhat fulfilling being able to hack my way through it all for a pretty good result (so far).


Attached is a pic of what I'm up to at the moment with the chipboard (and how much I need to clean up my shed). I'll stress that this is only a test for the jointer specifically.

The board is 1800 x 250 and will take sanding sheets in the landscape position. When the glue for this rail has dried I'll flip it over and measure just how flat it is along the length as well as width. If it's looking ok, I intend to put some ribs across the width, using the same clamping method, to try and keep it flat in that direction too.

I do have a little doubt that this isn't going to work (be flat and stable enough), but it's worth a shot. I'll be pretty impressed if a lowly bit of chipboard could get both jointer tables to within .05mm across both of them.

Hi again.
Seeing you are in Ballarat, you should definitely get in touch with 'Steamwhisperer' (Phil). He is the metal and steam maintenance man at Sovereign Hill and has access to macines you haven't dreamt of - woodworking and metalworking, both at work and at home. He also has connections with our friends with BIG surface grinders.
Send him a PM and ask to meet him. You won't regret it, he's one helluva nice bloke.

He sure is a nice bloke. He's already helped me out once before flattening some brass I'm intending to use for a shop-made square. If I get into a trouble I'll give him a holler.

Well well
I'm in Ballarat to well most weekends that is

Originally Posted by Simplicity

I'm in Ballarat to well most weekends that is

Well if you're ever at a loose end when you're here, shoot me a PM and come out for a visit. My workshop and gear is nothing particularly special, but it's always nice meeting other forumites and havin' a yak

Oh, and if you're here this weekend, there's a pretty good wood and craft expo on in town: https://www.woodworkforums.com/f25/ballarat-wood-craft-182759
More details: http://www.ballarat.vic.gov.au/lae/e...=2014&id=31230





There's been some slight drama this afternoon As Joe said, metal flexes, and when I tighten up the outfeed table to the machine base it makes an almost .10mm convex across the width right at the mouth (and that's as much as I bothered to measure in my new found misery). So for the moment I need to take a little break while I think about the next step (and get some new grub screws and stuff). It's not really *that* big a drama, but I'm a bit worn out and miffed that I didn't see it coming.

So in the mean time, and to keep with the theme, I'm going to try and get this whiskey to within .05mm level with the bottom of the bottle

The tale shall continue after Tuesday (or thereabouts).

I'm coming over to Ballarat in the next week or so (to visit Phil). I'd love to call in. I'll bring some measuring gear etc if you like. May be we could all meet at your place?

Dagnabbit...I'm really very sorry that I didn't get back to you Joe. Simplicity popped over for a while and I completely forgot. Much with the embarrassment


Anyway, Both jointer tables are now pretty much flat minus a small patch in the middle of both where it's down .05mm. The mouth end of the outfeed table also has a tiny bit where it's also .05mm down in the middle. It was certainly much quicker doing the infeed table in-situ. Obviously (now) doing the outfeed table unmounted caused a problem that needed to be corrected when it was back on the machine.

In the end I scapped the long board idea and used my chisel sharpening plates (glass on MDF again, a bit bigger than A4 size). I focused on getting the high spots down before doing long strokes over the full length. It worked a charm with a sheet of 80 grit wet and dry.

Alongside a clamped straight edge I belt sanded the wing where the blade guard is mounted to get it just below the level of the table. It was poking up considerably and would have caused the sanding plate to ride up. That area isn't a "timber surface" so it's pretty rough.

It is entirely possible to get the tables even flatter but quite frankly I'm a little over the sanding at the moment and would like to see how it performs as is.

I've shimmed the guts out of the outfeed table in the dovetail slides and have it within .05-.1mm coplanar with the infeed. When I put the knives back in I'll remove the multitude of shims and try to find something that's approx. the total height to get the layer count down to 1 or 2 and close up the remaining gap in the accuracy then. Generally I'm allowing myself a .05mm margin of error everywhere, but if I can make it a tight .05 then all the better.

Still lots to do on the bandsaw.