Refurbishing Biax BL40 Scraper #2

[mm289]

So continuing the theme of trying to create a resource library of how these things are put together and following on from the successful rebuild of my 7EL I am about to start on the next one.

This is a BL40 and is the later version of the the general purpose Biax scraper. It is as far as I now the successor to the 7EL and is still in production today.

These are all green whereas the earlier Biax's were all blue and look something like this.


These have the advantage of a variable speed control built into the end of the motor casing and use a slightly different arrangement for the blade guide to run on.

This rebuild will be a bit different also as I intend to re-motor this 110v machine to a 240v using a motor from a Metabo jigsaw as pioneered by our own @Pete.

So lets see how this one goes, hopefully won't take 15 months this time (famous last words )

Cheers,

MM

 

[mm289]

So starting with removal of the head. this is the same as on earlier Biax's just remove the 3 nuts and the scraper head pulls of whilst disconnecting the pushrod from the wobble head.

There is a hole in the gearbox to slot a thin rod through and lock the motor then you can unscrew the wobble head and remove.

The cage is different in that it looks like a different type alloy casting (bronze colour) rather than the grey of the 7EL



To separate the gearbox from the motor end plate there are 4 recessed allen screws


and then the assembly separates like this.



A couple of differences I immediately noticed is that on these the layshaft runs in small needle roller bearings rather than just bushings. Also the layshaft uses metal gears whereas the 7EL had a composite gear.




Other than that the construction is the same.

The head end of the gearbox has the same setup with a larger bearing held in place with a thrust washer and screwed retainer. the retainer on this one must have been done up by hercules and took some shifting. It is a conventional thread, just incase you come across one that is stuck and wonder if it is a right hand thread



This is a shot before I removed the gear and bearings just so you can see where they sit on the main driveshaft

Both look to be snug up against the respective shoulders on the shaft.



I will do separate pictures and note the bearing numbers for reference, but the ones on this machine feel really smooth so I may get away without having to replace them this time. Even the wobble head bearing had no movement at all in any axis.

The bearings are in soaking prior to cleaning and inspecting properly so will photograph when that is done.

Cheers,

MM

 

[mm289]

One of the intentions with this one is to re-motor it from 120v to 240v. As said earlier Pete has done the hard work in identifying a tool with the same motor and done a build before so I am following in his footsteps (hopefully)

The tool you want to look for is a Metabo ST EP 565 240v version as per below.



I picked one up off ebay for about £35 I think and was lucky as apart from some sawdust it seems hardly used. Its almost a shame to break it as it is a lovely piece of kit.

I am basically after the windings and armature so started by removing the rear cover for the motor then splitting the case





The switching and speed control is very different on these so not much you can swap over but I took lots of pics to remember how it was wired, although my crash course in AC motor wiring probably thinks it isn't necessary as I will just copy the way the 110v motor is wired....

This is the switch


With the electrics disconnected you can start pulling apart the gear end, removing the gearbox to this stage


The disc with the drive peg is held on by a very tight allen bolt, but once this is off you expose 2 screws that hold the gearbox to the case. You can then pull of the gearbox and the armature will come with it as the gearbox end bearing will be sitting in the gearbox housing.

Next job is to remove the windings and armature. This is the same process for the jigsaw and Biax as the housing (apart from the switch) are very similar. (Biax on left)



After removing all the wires and recording where they run too the windings are held in place by 2 screws (Biax is the top one) and just pull gently out



Biax on right



And the armatures can be compared (Biax on left)


As you can see the armatures and windings are identical, just one is 110v and one 240. Not sure what the difference is - perhaps one of the leccy experts would like to explain?

What is noticeable is how much cleaner the jigsaw motor is, it really does look hardly used. The armature bearings are like new and the whole motor is very clean.

So these are the motors stripped, next job is to transplant the jigsaw motor into the Biax and try to wire it up correctly........

Cheers,
MM

 

[brightspark]

[QUOTE="mm289, post: 1743718, member:

T
As you can see the armatures and windings are identical, just one is 110v and one 240. Not sure what the difference is - perhaps one of the leccy experts would like to explain?



Cheers,
MM[/QUOTE]the 240v winding will be thinner than the 110v one. the higher the voltage the lower the amperage the lower the voltage the higher the amperage so needs thicker cable to handle it

 

[mm289]

the 240v winding will be thinner than the 110v one. the higher the voltage the lower the amperage the lower the voltage the higher the amperage so needs thicker cable to handle it

Cheers, so is that the only difference then? Basically just down to supply voltage dictates wire/thickness of windings? And is that the same for coil and armature?

Just curious really, like to know how things work, probably why I have so many "projects"

Cheers,

MM

 

[brightspark]

Cheers, so is that the only difference then? Basically just down to supply voltage dictates wire/thickness of windings? And is that the same for coil and armature?

Just curious really, like to know how things work, probably why I have so many "projects"

Cheers,

MM

yes armature and field coils

 

[Matthew Tinker]

MM,
out of curiosity, try an ohm meter across them, I think the answer lies within!

Cheers, Matthew

 

[Pete.]

The field coil will be half the ohms on the 110v model. I never tested the rotor and in fact the reason I had to swap a motor was because the armature was knackered.

 

[mm289]

Every day a school day eh?

So started on the "heart transplant". Have deliberately made this quite picture heavy just incase anyone wants to try and repeat the process themselves.

I started by sitting the two coils side by side and numbering the coils/wires so I could make sure I had them in the same positions i.e. live and neutral going to the same place and the wires from the two other positions feeding the same locations (brush and rheostat from memory). No idea if this makes a difference TBH, maybe someone can continue to educate me on motor building



Then had to shorten the wires to roughly the same lengths



With that done feed the coil back inside the housing and route the wires through the appropriate gaps. Secure the coil with the two philips head screws



I then mimicked the connection from the 110v coil
This is gonna be real hard to explain and I might try and do a wiring diagram but basically....

The black coil wire goes to terminal 1 on the switch - this is the live feed from the mains. Routing is pretty simple as it just goes straight up and across (black with long yellow heatshrink on it)

Whilst on that side the white wire from the coil on the same side terminates onto the brush on that side. Its a tight squeeze so you have to be careful to cut the wire the right length and fit a ring terminal. This is the wire with the short yellow heatshrink on the bottom right of the above pic. The white wire on the same terminal is from the rheostat.

The "neutral" wire is the white wire on the coil opposite the black "live" wire. This routes up and through the body to attach to terminal "2" on the switch seen here on the left



The second white wire from the coil on that side terminates on the screw halfway up the body on the right. (white wore with black and yellow heatshrink in the pic below)

Also on this screw is the black wire from the rheostat



And that's it, the motor is wired........

Next job to test it

Cheers,

MM

 

[Pete.]

The motor will work fine. What will be interesting is whether or not the speed controller copes with the jump from 110v to 240v.

 

[mm289]

The motor will work fine. What will be interesting is whether or not the speed controller copes with the jump from 110v to 240v.

Your too dammed good at this Pete - how did you know

Thats exactly the problem I am finding - see next post which I am just compiling at the moment

Cheers,

Paul.

 

[mm289]

Typing this up whilst eating supper so bit of a delay. Would love to say I did a @doubleboost and ran up some culinary feast but it was a couple of pieces of breaded fish out of the freezer and some oven chips

So putting the rest of the motor together is pretty straight forward.

Both armatures are identical as you can see from the pics


The only difference is the Biax was running open bearings which was a bit of a surprise in a motor, the metabo had sealed bearings.

As the metabo was in such good condition I haven't change the armature bearings but for reference these are the numbers


You fit the dust shield into the body and make sure the brushes are out of the way and the armature just slides in



The brush/commutator end has a dust shield for the bearing. If you push the armature in fully this binds on the housing as it is a rotating component. i put a small amount of grease on this and didn't fully push home as per the pics below.



This allows the armature to spin freely, and I confirmed this approach by stripping the second BL40) i have and this also had the dust shield sitting slightly proud.

You can then mount the motor end case/gearbox mount and the front bearing pushes into this. At this point the armature is fully secured (even without the mounting bolts that fit through the gearbox so I went ahead and completed the wiring to the mains ready for testing. (note, in this pic the brown retaining board is 90 degrees out, it should be east/west not north/south.



And then for the test........

So it started first time yay the only challenge as Pete mentioned above (must have psychic powers ) is that it runs smooth as you like on full power, but when you dial down the speed on the motor it starts to feel a bit lumpy - like its missing on 1 cylinder if you know what I mean

Feels like the phasing or something isn't quite right. Still runs fine and once the inertia of the gearbox and head is attached it might smooth it out a bit but its not as smooth as the other 110v.

I guess all that additional componentry on the jigsaw circuitry must be smoothing the current somehow (or I may be talking bo**ox )

Still, the heart transplant has worked, now to rebuild the gearbox and see how it performs

Cheers,

Paul.

 

[mm289]

With the motor ready its time to assemble the gearbox. Basically the same process as for the 7EL, but for completeness I have recorded all the steps here.

The gearbox shaft, layshaft and 3 bearings get put together first, have included a close up of the bearings so you can see the ref numbers. As said before these all feel like new so I am not replacing bearings on this build.



The main bearing is pre loaded with grease and pressed into the gearbox housing and then the metal washer refitted before the retaining collar is screwed in.



I didn't like using a punch to remove/refit the collar so made up a tool to locate in the collar and tighten it



Then can press the second bearing and drive gear onto the drive shaft



And press the drive shaft into the gearbox housing. Then drop in the layshaft having preloaded the needle bearing with grease



The gearbox then mounts onto the motor casing with the 4 allen bolts.



It is worth noting when you fit the motor casing there are 4 brass pegs that go between the alloy casing and the plastic motor case (see previous post)

When you fit the gearbox casing to the motor case there is only ONE brass peg. Don't panic , you haven't lost 3 pegs. One of the receiving holes is larger than the other 3 and the peg will only fit in this one. This ensures the gearbox to motor orientation is correct.



Cheers,

Paul

 

[mm289]

We can now assemble the wobble head.

First off preload the bearing with grease, slip the retaining ring on the drive peg and press the bearing on before fitting the circlip



Then press the peg/bearing into the cage



And screw in the retaining collar



The cage can then assembled into the head and held in place with 3 retaining screws, again checking the orientation of the cage. Fit the allen head bolt, castle nut and retaining pin. When assembled correctly the drive peg should move between vertical and away from the head on the ALLEN HEAD side. Conversely on the retaining nut side it should move between vertical and into the head (towards the motor)


Then lock out the drive and tighten the head onto the driveshaft



And that's the box all assembled. The next bit is the scraping head which I will do a separate post on as there are quite a few pics.

Cheers,

Paul.

 

[mm289]

So the scraper head and shoe is slightly different on this to the earlier models.

The blade holder is the same, so blades fit all models but the shoe and the way it sits on the head is different.
There was very minimal play on the shoe, .20mm or 8 thou

When you remove the blade holder the shoe mounts to the flat on the ram in the same way with two screws

One of the differences is the two grubs screws you can see in the above pic on the outside edges of the shoe. These go through the top of the shoe and press against the bottom as seen in the pic below.

I'm not sure what these are for but suspect they may be to allow you to adjust the clearance between the shoe and the head. The only downside to this theory is I would be surprised if you could put enough pressure on the bottom edge of the shoe with these grub screws to make any difference......

The reason I suspect this is what they are for is that the surface they run on in the BL40 is just a flat insert with no adjustability. On the EL 7 the shoe runs on a wedge shaped block that you can move slightly and hence adjust the height.

This isn't possible on the BL40 as the flat insert simply sits on the head and is secured with pegs - there is no adjustability.

This is the head with the inserts removed

And a pic of the inserts, shoe and blade holder removed.

First job was to clean up the mating surface on the shoe where there was very slight wear visible.

I just used the hand scraper and a stone to clean this up.

As you might have noticed in the earlier photo one of the retaining pegs for the inserts was missing. It looked like one had been replaced previously with a piece of roll pin so I made the same repair to the other side then refitted the inserts.


Run out of allowed image uploads on this post so will put final assembly on the next one

Cheers,

Paul

 

[mm289]

So final assembly involved greasing everything and connecting the shoe rod to the wobble head

One thing I noticed different on this one is the inside of the head has an insert for the rod to run on, don't remember seeing this on the EL 7

And then assembling the shoe


Then to try it out.

I have to say it runs really nicely. Interestingly you can't really feel the motor hesitation when you use the variable speed controller, the inertia of the wobble head and shoe seems to smooth that out.

If anyone has any views or comments on the speed controller and issues with the motor hesitation then please add to the thread

But apart from that well pleased, another refurbed very nice Biax on the bench



I think I will keep this one for myself, so now to see if I can find time to strip and rebuild the other EL 7 and BL40, and whether to re-motor the 2nd BL40 to 240v or leave as 110v.........

I am also bidding on an ancient 240v Lesto nibbler on e-bay that "might" have the right size motor for the EL 7 so we will see how that progresses

Cheers,

Paul.