Radial Arm Cut Off

A lot of images are included here to aid in reassembly.

This is the unit I am starting with.   Sorry about the light from the windows.   In its first life a circular saw was suspended from the arm and it was a stand in for a radial arm saw.

The particle board spanning the legs has sagged under the weight of the arm.   I supposed one should not fault it as it 30 or more years old.   A quick look but did not find a similar one online.  

It is covered with years of filth and oxidation. 

The arm pivots but reluctantly.   

The thing has two protractors.   One at the base of the leg and a plastic one clamped to the bar about 1/2 way up here.

Two large nuts on this threaded bar clamp the upright to particle board.  The threaded rod is behind the particle board.  On could place it anywhere, like on a workbench.

Top side of the carrier that slides on the arms.

The center hole on this clamp is for the upright threaded rod.  The left side takes the longer of the two horizontal bars which is threaded.    The other bar is shorter, unthreaded, and goes on the right behind the carriage head bolt.   But not sure how it is held in place.   Need to look at that again.  Missing image ?

The front end of the guide bars.  They push into this bracket and are held in place with two socket head cap screws.

To aid in disassembly the rails have been hit with a bit of sandpaper.  

Drilled centers in the threaded ends of the rods and polished them on the lathe. 

-----------------------------------
Tuesday

Found an excellent video by JSK-koubou.    Angle Grinder Sliding Cutting Jig

This is what I want to do but simpler than want I was thinking.   My linear bearing setup is horizontal instead of vertical but a stout bit of angle iron will fix that.   Initially I will build it without the nice thrust bearing he used but should work.  Am making a little different setup to attach the grinder to the wood.  Plan on making it so I can more easily swap out the grinder and not change the wood.   Each grinder will have a metal bracket with the same spacing between the bolts.

I have cut the mounting angle and have it soaking in vinegar.  It is old and pitted but quite thick so will be OK.  If this works I may treat it to a sandblast and some bondo.  Maybe.

Started work on the mounting bracket for the grinder.   Bent one up in the press brake but the arms going to the holes on the grinder need to be slightly longer so it can pivot.   Had to go downtown and pickup a bould of M8 bolts.

New fence on the press brake is working well.  Currently it is only constrained from moving away from the dies.   Thinking about some way to prevent it from moving toward the dies.  That is not too much work.  EDIT:  The easiest thing would be to make the spacer block used to set it L shaped so they can hook over the fence and not fall down.  That should be good enough and really only needed when making several.

If all goes well I can have the grinder mount finished tomorrow and make the first version of the wood handle.   Thinking of attaching a 3 or 4" steel disk to the face of the wood handle and have it rotate against the mounting angle.   That or use a ball bearing from stock.  Thinking the plate would give more stability

---------------------------------------------------------------

Wednesday - snowed last night, high of 40F today.

Continued with the grinder bracket.   The plan is to weld a wider bit of flat bar to this and bolt the flat bar to the wood handle.  The first bend interfered with the second bend.    They make hook shaped dies for this purpose.  So I had to finish it by hand.  The top is got a little curved in the process.  It is just a little too narrow to fit over my anvil so I can't easily hammer it out.   Maybe good enough.

I have been thinking about mounting the handle to the bracket on the linear bearing.   Initially I will make it simple as possible just  to get it going.   Then use a bearing of they type from the HF cement mixer drum.    If it is not too big. 

The vinegar the bracket is soaking in has slowed down or stopped working.   Don't know if it is used up or if the rust has stopped reacting with it. 

I should explain that I am working on this from 2 directions.  From the grinder out and from the linear bearing out.    When they are finished I just need to do the bits in the middle.   

Should mention I am a bit apprehensive about this becoming a rabbit hole.   To use the ball bearing I would need to cast and machine a few parts.  That could take a few more days thus the KISS for now.

Am also concerned about the grinder hanging off to the side of the linear rails.  JSK-koubou arranged his rails one above the other.  Mine are side by side with the angle grinder to one side.  The grinder is light it should work.

Going to have some popcorn then go back out and finish the grinder bracket.  Ah maybe save the welding till tomorrow when the sun is out.  I hope.  Took the linear bracket out of the vinegar.  Maybe drill the holes in it.

Took a nice long break.  Took the linear bearing bracket out of the vinegar  and blued it and then took the linear bearing apart.  The rollers look to be phenolic.   Will see when they are cleaned.  Has white grease with a bit of a yellow tint.  Lithium maybe.

Have the bearing sorted. Do it now and not have to revisit it.  Machine an aluminum bearing holder with a flange from a pulley blank.   Bolt the flange to the wood handle with a cutout for the bearing bit.   Use threaded rod for the axle.  Machine a tube that threads over the axle with the same OD as the bearing ID.  Use loctite bearing retainer to glue the bearing into the holder.   The stack up for the bearing will be all metal with the handle bolted to the holder flange.   Bore the center hole for the flange with a forstner bit and turn the OD of the flange for a nice fit.   

There is so little side load on the bearing that any will do.  Will try for a deep groove if I have one.

-----------------------------------------------

Friday

Last night in the wee hours I glued up a blank for the handle.  About3AM I ran it through the surface planer.

Today I cleaned the linear bearing in the ultrasonic cleaner and lubed it.  Used dawn for the die cast parts but one.  That went in with the bolts and such with royal purple.  It dulled the surface.

Shortened one leg of the mounting plate and drilled holes to attach it to the linear bearing.    Shot a short video and uploaded it here.  Does not seem to work so may have to use YouTube.

 

Scratch built Acute Tool Sharpening System (Part 1 table)

Ordered the plans and started construction of the Acute Tool Sharpening System.  So far I have built the table stand.  It is very rigid.  Still working on the friction disks which hold it into position.  And obviously deburring and some sort of finish.  Paint would not work well.

The plans are metric but I am using imperial material and hardware.  1/2" bolts instead of 6mm.  That sort of thing.   The parts were roughed out of steel with the angle grinder then cut and filed to final shape.   Filing buttons were used for the round bits.

Tried gluing the paper pattern to the plans but it was miserable.  Switched to layout fluid and scratching with the digital caliper and scribe.   I was able to find the intersection of lines with the tip of the automatic center punch, thanks Chirpy.  

As it currently existed the DIY fence on the 4' hydraulic finger brake (discussed elsewhere in this blog) did not come close enough to the die.  But its just a chunk of angle iron bolted to a butchered 4x4 so some quality time with a forstner bit allowed it to accommodate the offending bolts. 

The angle parts were cut from a lawn tractor frame.  Its 1/8" just a bit over the 3 mm called for in the plans.   

Filing buttons were used to shape the curves.  The paper covered part to the right is a failed attempted at using paper templates glued to the steel.  I guess that's just for wood.

The slot in the links were chain drilled then an 1/8" end mill was used in the drill press to clean it up to where I could use a full sized file.

The friction disks that hold the unit in position were cut from 3/16" hot rolled steel using a hole saw.

1/4" bolts were used a mandrels.  A nylock nut captured the disk on the bolt which was inserted in the collet to turn the OD and bevel one side.

Here I drilled a center in the bolt but did not use is.  Similar but longer mandrel/bolts were used to turn the OD of the aluminum spreaders and the tailstock was used to support them.

The friction disks after turning.   At this point I still have to cut the groove on the other side for the o-ring.

And at this point I have what is show in the first photo.

The following image from Ecentric Engineering's site shows it loaded with accessories.   My initial intent is to sharpen lathe tools so I will not be building the fence and other stuff I don't need.

I have the table roughed out of 3/16"  It really does not need to be square but I intend to have a go at it.
I may try 3D printing some of the parts.   Yeah grinding and plastic are not a good match but let's see how it goes.

------------------------------------------------------------------------

Busted the tip off the grooving tool as I was finishing the first friction disk o-ring groove.  Used the table with a filing button standing in for the unfinished friction disk.   I have the table bolted to a board that is clamped to the board holding the grinder.   I became obvious that I needed to grind on both left and right side of the cup wheel.    OR IS IT???  The table was designed for a standard grinding wheel  so it is to short.  I was able to reposition the table using the clamps but it is far from idea.   Thinking about making a much wider version.  Really just a wider table and wider spacers.  Might require modifications to the bits on top the table.

Have the grinder clamped to the roll around table (bit of scaffolding).  So I ran it outside to true up the lip of the cup wheel.  My diamond wheel dresser is in hiding so I used a stack of lock washers on a 1/4" bolt.  After that I adjusted the table and set to regrinding the broken bit.
Having said that it worked wonderfully.    Not sure if the shape is correct but the grinding was easy even fun.  The wonder of using a balanced wheel or maybe the cup wheel contributed.  All good.

When mounting getting the table true to the wheel is a bit daunting.   Maybe replace the two lower brackets with a single U shaped part with a central single mounting hole.  That would allow the table to rotate to align with the wheel.  Just need to work out how to keep it from moving.   Should not be a big deal maybe just torquing it down will be enough.  Making the bends will be interesting.  

Need to workout a wheel guard.  There is not much room between the back of the wheel stack and the motor.  So maybe a plate similar in thickness to the original guards with a cast aluminum tube that bolts to it.  If there is any dishing to the original plate that bolts to the motor I may have to cut the backing plate from it.  Would rather not ruin it.  Just in case I want to use this unit with regular wheels some time.

----------------------------------------------------------

I am thinking of making two more units with larger tables more suited to the cup wheels.    This will also require new spacers.

Maybe add a second bolt on layer to form a miter slot.   It will allow simple jigs to sharpen bits till the rest of the system is finished.  Don't need that till I need to sharpen milling cutters.

Found an interesting vid on 1 Hour Red Rust Bluing on theCogWheel channel.    An hour is a bit painful but there are no chemicals to buy other than common household items.