Thread: Buying a rack

Originally Posted by BaronJ

As I recall the rack was only about 120mm (4,5/8") long and 1/2" wide. It was to repair a broken microscope table. The gear was OK and the original plastic rack with the broken teeth used to get the cutter profile. But the bar that I used to hold the cutter was a length of 3/4" silver steel with a cross hole drilled and then cross drilled again at 90 degrees threaded for 2BA hex grub screws. One screw in each side. The bar was clamped in the three jaw at one end and sat on the live centre at the other.

OK so a short length and a very fine DP therefore small tool. And in brass. That's a lot different animal to a bigger and longer rack in steel. I can easily do short lengths using the Y axis feed on a mill. For long racks it gets more difficult.

Short form:

Grind a tool to the correct angle of 29 deg for a 14.5 deg PA.

Set up a single axis DRO or similar because you need accurate tooth to tooth spacing and accumulating errors are a real risk.

Use a spreadsheet or whatever to calculate all the moves from tooth to tooth.

Add an auxiliary table extension to the side of your shaper to get max benefit from the travel before having to reset everything.

Cut the first tooth to full depth hand-feeding the cutter because you don't have power downfeed and are too lazy to swap the table drive to power upfeed.

Index across.

Cut the next tooth to full depth.

Repeat until bored totally witless.

PDW

Originally Posted by PDW

Incidentally this talk of racks reminds me I have a spare rack for a Monarch 10EE lathe - also 14DP - that a friend of mine in the USA sent me some years ago to adapt to the Chipmaster if I thought it would work. I never used it and it's taking up space somewhere in a cupboard. It's yours if you want it. I've also got all the 14DP cutters you could borrow if you want to or need to make another pinion gear.

PDW

That would be nice, the rack on mine is a bit sad.... I put newer second hand gears into the apron, so the pinion is pretty good...

I assume there are two pieces about 300mm long or something like that...

Originally Posted by .RC.

That would be nice, the rack on mine is a bit sad.... I put newer second hand gears into the apron, so the pinion is pretty good...

I assume there are two pieces about 300mm long or something like that...

I'll dig it out in the next couple days & email you a photo or 2.... it's 1 piece.

PDW

Originally Posted by PDW

Cut the first tooth to full depth hand-feeding the cutter because you don't have power downfeed

May not have helped. I find it too coarse for plunge cutting. I have to hand feed in very fine increments.

Hi PDW,

Cut the first tooth to full depth hand-feeding the cutter because you don't have power downfeed and are too lazy to swap the table drive to power upfeed.

Index across.

Cut the next tooth to full depth.

Repeat until bored totally witless.

PDW

Yes that's just about how I remember it. Though in my case, whilst I had power crossfeed I couldn't use it because I was using the leadscrew to index each tooth.

Ok. I think I just accidentally learnt something here….. The ratcheting cross feed on the shaper, can you move that and re-connect so that it ratchets the feed on the up/down on the table?

Simon

Originally Posted by simonl

Ok. I think I just accidentally learnt something here….. The ratcheting cross feed on the shaper, can you move that and re-connect so that it ratchets the feed on the up/down on the table?

Simon

Some can - my Prema being an example of that. Must say I've never used it but the gear fits there & meshes correctly with the other one, there's the proper keyway etc..... planers work the same way basically, you move the gear to determine cross feed or vertical feed.

PDW

And some can't, the queens rise and fall shaft comes out the other side of the saddle. Plus the table and saddle is so heavy and the gearing so fast (its not really but it is compared to say the mills rise and fall) I would think something in the ratchet would break if you could hook it up.

Ew

Originally Posted by simonl

Ok. I think I just accidentally learnt something here….. The ratcheting cross feed on the shaper, can you move that and re-connect so that it ratchets the feed on the up/down on the table?

Simon

I made a small mod to my Douglas so it can use the ratchet on the vertical feed. It works well, but requires vigilance to stop things jamming as the table rises and the geometry changes drastically....

Originally Posted by jhovel

I made a small mod to my Douglas so it can use the ratchet on the vertical feed. It works well, but requires vigilance to stop things jamming as the table rises and the geometry changes drastically....

That sounds like a worthwhile mod.

Cheers,

Simon

Hi Andre,

I had a bit of spare time today and since it was too hot in the shed, I decided to go to my usual scrap metal place to see if I can find some more material for my sheet folder. It's been a slow process but a very economical way of sourcing the materials for this project.

It was slim pickings but I found some racking. I intend to use it for the finger clamping, since they are in 1230mm lengths. While this material will suit my purposes extremely well, I'm happy to offer you some if its what you need.

The rack has a pitch of 5mm and a tooth depth of approx 3mm. It's approx 25mm x 35mm and has holes pre drilled at 100mm centres. It's pretty hard but can be filed. No visible signs of wear. It cost $1/Kg which equates to about $7 per 1230mm length so virtually free. In fact if you can use a small quantity of it them I'll be happy to post it off to you free.

Some pics. Let me know….

Cheers,

20140206_195328.jpg20140206_112850.jpg

Simon

Hi Andre,
Simon and I were talking and I had another look in my useful draws as a result. This is what I found. Looks like 1/4" pitch than his bits PLUS matching gear. Its about 410mm long.
Same deal: they're yours if you want them.

thanks for the offer guys but the rack is question is meat to be 3/8 x 3/8

No worries Andre.


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