Repairing my shaper, an ongoing saga.

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Oct 7, 2023
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Brighouse. Yorkshire, UK
I got the shaper free when I bought my Colchester Chipmaster lathe oven 25 years ago and have had issues almost since then. The first thing wrong was that there was no motor fitted so I fitted one. Rather too small as it turned out, but it did the job. So we had a working shaper, which was a fabulous bonus as it was for nothing.
Then I became aware of certain repairs that had been carried out some time previous as the dovetail bit holding the top slide fell off. It had been pinned together and some evidence was found of soft solder or something similar.
I was unable to find a source of a new part, so, for the short term, I machined the stump to accept the clapper box. This is how it is in this video:-

The eagle eyed among you will spot the "welding" holding the top of the clapper box on. Well that fell off quite recently so an attempt will be made to silicon bronze braze that back together.

I started the plan for the replacement part almost as soon as it first broke, but without a milling machine or a shaper that could cut the dovetails, I was a bit stuck. I did manage to source a lump of (quite nasty as it turned out) cast iron from a customer's scrap bin. The place has since closed down but were a company in Hull who specialized in making continuously cast bars from various types of cast iron. The few bits that accidentally fell in my van were the end bits which are not the same stuff as the rest of the bar as it gets drawn out of the mould. I know why they scrapped these quite well now, but that's many years ago.

The lump being ruined in the shaper in the above video is the starting point for the new component.
Once the part was squared up I began to carve it to the correct shape. 20240215_180520.jpg

The scribed lines are for the first cut (top line) and dovetail layout (line just above the rust)

The slide bit looks like this and I was trying to make the new part suit it.20240215_180526.jpg

I ended up with a part that looked like this
The dovetails are cut off-centre as theres a gib on one side. The top hole fits the bronze nut for the feed screw and the lower hole is a temporary 20mm bore to allow me to sit the whole thing on the rotary table. The table is a 3" diameter baby thing which came as a freebie with the milling machine.
The radius on the bottom is to allow the ram to pass backwards without knocking the new bit off.
The pins from the attempted repair can be seen in this photo. You will see why the repair was less than successful, but I'd misremembered how the machine was originally put together. I'd assumed that the dovetail bit bolted on as I'd done with the clapper box last century.

My first attempt was like this, and it became imediately obvious that the screw thread would pass through the mounting bolt (or not, obviously)PXL_20231227_151808475.jpg
Good work! I love my little 7" shaper - not the fastest tool in my inventory, but very satisfying to see it peel off metal. I need to fix an annoying issue with the auto-feed pawl - it doesn't always want to catch when set for left-to-right motion. Not sure if a stronger spring or a sharper tip is what is needed ...
Feeling a little bit adventurous, I set out to cut the graduations on the slide mechanism. I used the rotary table and the temporary bore to get the part centred on the table. I fixed it down using a single M10 bolt through the bore once I'd drilled out my 2MT mandrel.
To get a zero degree mark, I put the part in it's intended position and marked where the zero mark is on the shaper ram. The slide mechanism will be very close to vertical, or should I say at a right angle to the tee slots.
The graduation cutting was a new thing to me, and I don't own the drag tool that seems to be favoured. I scratched around a bit to look through what I DO have and started testing. The YouTube is awash with CNC machines cutting these , mostly with a diamond tool.
I found that I had a carbide tipped scriber that's built like a clutch pencil and the tip is about the same diameter as a pencil lead. This fit into a collet, then into another collet as the ER32 didn't fit but the ER25 did.
Then, to a scrap of the same stuff that I cut off earlier to experiment with point loading to get the required scratch depth. Well carbide is brittle and doesn't like being bent, so as soon as I tried to drag it it snapped off.
Next idea was a pointy thing like a scriber, ground half way through, like a D bit cutter. Well, an actual D bit cutter. So the avaricious part of me was half way to Ebay to get hold of a D bit grinder, as I don't have one, but fortunately (or unfortunately, it depends how you look at it), the nausea caused by getting my hand in my pocket stopped me from acquiring the grinder. This is on the "find one, make one or do without" list now.
So next stop, freehand grinding a D bit point to spin in the mill to cut the groove. There was no way I could get the marks consistently the same depth. Either the quill has some vertical backlash or something to do with tool geometry, either way this didn't work.
Then, back to poking about in drawers, I came across a drag cutter. In a box marked "tap follower". Same thing, really, isn't it?
This worked really well, leaving clear marks that really stand out. A bit of bad driving of the rotary table caused a just noticeable variation between the scratches, but I was happy. The small degree lines were 5mm lond, five divisions 8mm long and the tens 10mm long, all measured on the DRO.
The euphoria went a bit flat when I cleaned off the Dykem as the lines faded. They're still there, and maybe can be filled with something black to improve contrast, I don't know.
Next job is to bore the centre to accept the spherical washer that holds this bit on, and to get a spherical ended boring bar to do it. or... Still wondering how to get a radiused bottom to the bore. The lathe is out of action as we had to borrow the VFD to drive a customers machine, so he gets the old one and my new one should arrive today. All the instructions are in Chinese, so that's good fun.
VFD came back and the lathe is now operational again. The boring was done and the dovetail bit fits. The gib strip is made out of sheet metal and wasn't not as flat as I'd like. Using a diamond sharpening stone was taking the edges off, by hand. Then it occurred to me that it'd be really useful if there was a machine that just reciprocates that I could use to do this tedious work.

A bit of double sided sticky tape, some magnets and I had a suitable "thing".
It ran flawlessly for an hour before the tape failed and the gib was thrown on the floor. In much flatter condition than before.
It might be handy to make a real setup to use the shaper in this way, maybe someone already did?
To hold the work-piece like that a magnetic chuck would most likely work.


Andrew in Melbourne
An interesting solution. Having said that the old hands in my factory would strongly disapprove of the use of magnets or tape for any operation other than very light grinding. With the possible exception of a lathe where you can apply counterpressure with the tailstock. Because of the risk that you describe of the whole setup falling apart thereby possibly damaging others, yourself, your machine or your workpiece.
An interesting solution. Having said that the old hands in my factory would strongly disapprove of the use of magnets or tape for any operation other than very light grinding. With the possible exception of a lathe where you can apply counterpressure with the tailstock. Because of the risk that you describe of the whole setup falling apart thereby possibly damaging others, yourself, your machine or your workpiece.
While not particularly applicable to most home shops, I suppose it depends on what kind of magnet and how old, but things have changed considerably from what you suggest, as well as how you do your setup on the magnets, there are some very strong magnets out there now, some designed for milling.
Thank you for a very interesting and enlightening tooling-movie. Alas my home workshop is loaded with tools and machinetools that come straigth from the 60's and 70's so what you show is from my time-capsule far in the future!
New problem / issue. The stopgap motor that I fitted all those years ago is rated at 600W. Must have been the biggest Machine Mart had on the shelf, maybe I got it just to see if it turns, who knows after all this time.
Now I'm wondering how big a motor do I need? 1.5kW? 5.5kW?

More research needed and your inputs and / or are greatly appreciated.
FWIW, the original motor on my 7" shaper was rated at 1/2 hp. It was 3-phase, which I didn't have at the time, so I swapped it out for a single-phase half-horse motor. For the speeds and feeds I use, that seems to be sufficient.
Thanks Andy, I've got a 10" one. Never thought I'd say that line. I found online an old newspaper advertisement where it's advertised with a 3/4hp motor. The associated web page tells me that a 1 1/2hp motor was an option as well.
I've decided to go with a 1 1/2hp 3 phase and run it through a VFD. This will allow me to run it slowly without suffering a loss of torque such that it's no use as well as starting the thing without the belt rending and noise.
10" - well now I'm jealous!

Many years ago, I was at an auction where I was hoping to buy a 12" shaper. No one was interested, the auctioneer wasn't even sure what it was, so I was very hopeful ... but just before bidding began, I heard someone say "I bet my friend would like that" - he called, and sure enough, they outbid me. :( It was at a time when money was tight, so I wasn't able to bid very high - they got it for a steal. I've always regretted that I wasn't able to bid higher ... though honestly, where I would put it in my over-crowded garage ... maybe it is for the best that I later "settled" for the 7". :)