first time on any kind of forum so please be kind. Just purchased a 1955 meddings pacera pillar drill with the intention of renovating it. Already found a few problems one being the two alluminium rack carriers have snapped where the two threaded bolt holes are. My question is do i have them welded or do i get someone to make new ones out of a more suitable material. For both of them to crack suggests to me alluminium isn't up to job. I am open to suggestions thanks.
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Agroshield
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What diameter and thickness are they?
A cheap replacement would be two large polo mints plasma or flame cut from steel and then machined to suit.
Price up aluminium rounds in the correct diameter as well as cast iron. M-Machine Metals has a good catalogue.
A cheap replacement would be two large polo mints plasma or flame cut from steel and then machined to suit.
Price up aluminium rounds in the correct diameter as well as cast iron. M-Machine Metals has a good catalogue.
RobCox
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Firstly, welcome to the forum. We're always kind here
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I'd guess it depends on whether they're cast. If so the material may not be the best in tension. I'd have thought a piece of machined aluminium round bar would be ok. They might weld up. In your neck of the woods @doubleboost is possibly your man.
.I'd guess it depends on whether they're cast. If so the material may not be the best in tension. I'd have thought a piece of machined aluminium round bar would be ok. They might weld up. In your neck of the woods @doubleboost is possibly your man.
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Screwdriver
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Looks like a weak point but it might simply have been abused in the past or maybe dropped.
Personally, I'd have them welded. It may be that the machine was functional even with the crack, else I would expect such a failure in service to be dramatically worse.
Personally, I'd have them welded. It may be that the machine was functional even with the crack, else I would expect such a failure in service to be dramatically worse.
zzr1200
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I would suggest that the Allen screw holds the rack and but possibly also clamps the collar to the pillar (
picture?). I use a shorter set bolt if the assembly should rotate around the pillar...
I agree with RobCox, @doubleboost is your man up that way to ask.
picture?). I use a shorter set bolt if the assembly should rotate around the pillar...I agree with RobCox, @doubleboost is your man up that way to ask.
Agroshield
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Given the location of the crack, they would need further attention after any welding. That is more involved than the welding itself.
The inside would have to be dressed true. The entire inside diameter would need to be verified true (no distortion) as they need to be a good fit on the column (there is a high possibility it will be egg-shaped after welding). The slot for the rack would need to be dressed true, as it needs to be a reasonable fit to the rack. The hole would need to be re-located, re-drilled and re-tapped so a drilling jig, made before welding, would be a good idea.
Thinking about it, it would be easiest to make as a pair siamesed, then cut in half and face the cut edges. If it is available in the right dimensions, a piece of thick wall tubing (hollow bar) would work.
On Meddings that I have seen, those collars rotate on the column so the table that slides up and down on the rack can rotate about the column. Hence they should not be clamped to the column, only the lower one prevented from moving downwards on the column. There are pictures of Meddings MF5 on lathes.co.uk so by looking at them we can work out what they do.
Edit: hopefully not teaching granny to suck eggs, but the OP should know that the rack and pinion is designed only to lift an empty table up and down on the drill. In particular, driving a loaded table upwars will strain those connections. Similarly, forgetting to lock the table, so the thrust from the drill bit is transferred into the rack and into the collar is also not good for their long life.
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Yes I think your correct, machining new ones is the way to go I think. Many thanks for your input much appreciated.
Thank you for your quick response
Thank you for warm welcomeFirstly, welcome to the forum. We're always kind here
I'd guess it depends on whether they're cast. If so the material may not be the best in tension. I'd have thought a piece of machined aluminium round bar would be ok. They might weld up. In your neck of the woods @doubleboost is possibly your man.
Yes it may have been abused who knows. Think I'll go with machining new ones from steel. Thanks for help
Yes I was also surprised. May be an attempt to reduce weight as this is an extremely heavy machine. Thanks for help.
They don't clamp to post but there is one countersunk bolt holding rack to column which I find strange. I think someone has added this at a later time. So the rack is in a fixed position. In my mind not a good idea as all weight of table is on that one small bolt. Strange.I would suggest that the Allen screw holds the rack and but possibly also clamps the collar to the pillar (
I agree with RobCox, @doubleboost is your man up that way to ask.
Screwdriver
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Given the detailed comment, I thought I'd reply if only to add balance.
The inside would have to be dressed true but how is that more cumbersome than remanufacturing the entire set from scratch. With a lathe that would be trivially easy, the external surface just needs to be dressed flat and the mounting hole remade. The rack itself is the ideal jig for finding the position of the hole.
These are not load bearing parts. The only loads during correct operation would be a tendency for them to "rack" and jam as they are rotated around the column. Hence my comment that they may actually have either been broken due to misuse or mishandling. Another strong possibility is the column corroded and "grew" causing the collars to bind up. If one or other of them is bound up, shifting the table would cause the vertical rack to twist and given the leverage with someone grabbing the table (or adjusting position with a hammer!) a lot of twisting force would present itself right in the cutout - via the mounting holes! The perfect opportunity to cause a fatigue crack even during "normal" use.
As I suggest above, these might have been broken for years and not even noticed since 1. they are bolted to a steel rack and 2. they carry "no" load other than trying to keep the rack vertical.
The aluminium should be of a decent quality given the vintage of the machine so welding shouldn't be a problem, though I must accept distortion could be an issue. However I would be wary of remanufacturing in steel because an aluminium collar is a lot less likely to bind on a steel column. Finally if the item is being restored, keeping things original is another compelling reason to repair the OEM item rather than remanufacture.
Good job I didn't suggest what I'd probably do myself which would be a toss up between turning a blind eye and judicious use of superglue...
PS I actually do have one of these tucked away in a garage somewhere, awaiting attention. One or two come to think of it...
Screwdriver
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Oh hang on so the rack has been immobilised! How does anyone rotate the bed position? What (do you think) would happen to the alignment collars if someone did try to rotate the bed with the rack held captive?
Sounds a bit like the main body has been transplanted onto a new column...
Oh hang on so the rack has been immobilised! How does anyone rotate the bed position? What (do you think) would happen to the alignment collars if someone did try to rotate the bed with the rack held captive?
Sounds a bit like the main body has been transplanted
Screwdriver
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If you go to EDIT and hit TOGGLE CODE, you'll be able to see what the forum software is doing with ur reply.
As teeth are on same plane I can't see any reason for not being able to rotate. In my humble opinion.
