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Making a Rack, how to secure to table?

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Reeltor

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#1
I am attempting to make a rack, the work is 2" X 4" x 40", the tooth size is #4 on a 16" G&E shaper. Here is some background, I hope I'm not too wordy. I don't have a shaper vise and tried to use a lighter duty 6" milling machine vise. The vise and work was pushed off the table, I think because the vise didn't align up with the table slots very well. I then clamped the work directly to the table using home-made T-nuts drilled out to use 1/2" studs that I use on the mill. The work was once again pushed off the table bending the studs. I'm either going to make or buy another set of T-nuts for 5/8" studs or bolts.
Here is my new plan, please let me know if you have a better idea or if you think I am on-track to get this machined.

I am going to look for a large piece of angle iron. Drill one arm of the angle iron to match the table T slots and use heavy duty C-clamps to clamp the work to the upright angle.
If this doesn't work, I think I'll have to drill holes in the rack and bolt it to the angle iron. The real question is how to prevent work from moving on the shaper table.

I am attaching two photos, one showing the partial stroke when the work was pushed and a shot of the first tooth cut

Second tooth.jpg

and one of the bent 1/2" studs
bent stud 2.jpg
 

benmychree

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#2
On planers this is prevented by drilled and reamed holes drilled into the table at regular spacing; stops that are simple round pins with a larger collar turned at the top are set in place so that the work bears against them so that the workpiece cannot slide off. G&E made an auxillary (larger) table that bolted down to the machine's regular table with tee slots and holes for the poppets and stop pins for mounting work as it is done on planers.
Poppets are similar to stop pins, but are taller, perhaps 3/4 - 1" and are tapped crosswise at perhaps 5 deg. for a cup point square head setscrew; poppet pins are short round hardened pins, sharpened on one end like a center punch and rounded on the other to fit into the end of the setscrew; the sharp end is pushed against the work from both sides at a downward angle and at an angle towards the stop pin; this holds the work against the stop pin and also holds it down against the table. BTW, at least on my G&E shaper, the vise is provided with a pin through its swivel base that fits into a hold drilled in the table.
I think there would be no downside to drilling and reaming a hole near the end of your table to prevent slippage of the workpiece, perhaps even several, but they should be accurately located so as to be all perpendicular to the table slots on the same center line.
 

rock_breaker

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#3
As a beginner on a shaper I read this post with great interest. No doubt there are a lot of things I have to learn and will with time like bit shape and sharpness, depth and width of cut. I have learned here that these machines exert a lot of force and work mounting is critical. Also adding a support table for special mountings has started a new line of thought.
A machine that can bend 1/2" bolts is certainly more powerful than my 7" shaper but no doubt many of the operating procedures and set-ups are similar. Something new is learned on this website every day.
Have a good day
Ray
 

benmychree

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#4
As a beginner on a shaper I read this post with great interest. No doubt there are a lot of things I have to learn and will with time like bit shape and sharpness, depth and width of cut. I have learned here that these machines exert a lot of force and work mounting is critical. Also adding a support table for special mountings has started a new line of thought.
A machine that can bend 1/2" bolts is certainly more powerful than my 7" shaper but no doubt many of the operating procedures and set-ups are similar. Something new is learned on this website every day.
Have a good day
Ray
If you think that a shaper that bends 1/2" bolts is impressive, think what a planer with 30 horsepower can do! Cutting 1/2" or more deep with 1/8" feed is nothing.
 

Superburban

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#5
I'm no expert, but I have played a lot with my shaper. I take it your tool is shaped to do the whole cut, and you are moving straight down. What I see, is the force to do the cut will increase dramatically as the tool cuts both sides, and the bottom. What I'm relating to, is a lathe doing threading, you angle the compound so you are mainly cutting one side of the thread.

Perhaps taking a smaller cut is what is needed. as you get deeper, you will still be removing lots of metal on each pass.

The other thought is to do one cut with a straight walled tool, to cut the main part, then go back with the angled side tool, to cut the straight cut into the Vee that you want.

I broke the end off my shars 6 inch vise with my shaper, so be happy you only bent the studs. If you want to do the full cuts, I would devise some bracketry to take some pressure off the end of the vise, and transfer it to the table.
 

Reeltor

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#6
If you think that a shaper that bends 1/2" bolts is impressive, think what a planer with 30 horsepower can do! Cutting 1/2" or more deep with 1/8" feed is nothing.
It didn't bend one 1/2" stud but 4, a lot of force is exerted. I wonder if the work started to slip and then locked up causing the bend.
 

benmychree

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#7
I machined a bunch of sections of rack way back in the day of steel, they were about 1 DP and perhaps 8" wide and 5 ft long; they took up most of the planer's 15 ft table. We first slotted them with a parting type of tool then used a left and right handed tool to finish each side of the teeth, using a sample template set up behind the start of the cut, I'd back the table up to set the tool to the template to take each finish cut. The previous post is entirely correct in suggesting this method, rather than a plunge cut to full form; best to rough out the center first.
Of course not everyone has a horizontal mill to do a job like is described, but that certainly is the preferred method, using a regular involute gear cutter.
 

benmychree

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#8
It didn't bend one 1/2" stud but 4, a lot of force is exerted. I wonder if the work started to slip and then locked up causing the bend.
That is quite long at 40"; depending on what material you are using, expect it to bow considerably, especially if you use cold rolled. This is caused by the rolling stresses being relieved by removing so much material from one side.
 

Reeltor

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#9
I'm no expert, but I have played a lot with my shaper. I take it your tool is shaped to do the whole cut, and you are moving straight down. What I see, is the force to do the cut will increase dramatically as the tool cuts both sides, and the bottom. What I'm relating to, is a lathe doing threading, you angle the compound so you are mainly cutting one side of the thread.

Perhaps taking a smaller cut is what is needed. as you get deeper, you will still be removing lots of metal on each pass.

The other thought is to do one cut with a straight walled tool, to cut the main part, then go back with the angled side tool, to cut the straight cut into the Vee that you want.

I broke the end off my shars 6 inch vise with my shaper, so be happy you only bent the studs. If you want to do the full cuts, I would devise some bracketry to take some pressure off the end of the vise, and transfer it to the table.
The shaper has auto-downfeed, I think I'm taking .003 per stroke. While I agree that the deeper the bit goes the more metal is removed, I see videos of similar shapers taking 1/2" cuts 3/8" deep per stroke. I am a novice on this machine, I thought I was well below the maximum cut per stroke.
I am no longer trying to use a vise for this job.
 

Reeltor

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#10
I machined a bunch of sections of rack way back in the day of steel, they were about 1 DP and perhaps 8" wide and 5 ft long; they took up most of the planer's 15 ft table. We first slotted them with a parting type of tool then used a left and right handed tool to finish each side of the teeth, using a sample template set up behind the start of the cut, I'd back the table up to set the tool to the template to take each finish cut. The previous post is entirely correct in suggesting this method, rather than a plunge cut to full form; best to rough out the center first.
Of course not everyone has a horizontal mill to do a job like is described, but that certainly is the preferred method, using a regular involute gear cutter.
This is the exact method I used to cut the gear to mate with the rack. The length of the rack prohibits me from using the horizontal mill to cut the center out of each tooth. This is hot rolled steel, I am hoping not to have too much curling of the blank.
 

Superburban

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#11
The shaper has auto-downfeed, I think I'm taking .003 per stroke. While I agree that the deeper the bit goes the more metal is removed, I see videos of similar shapers taking 1/2" cuts 3/8" deep per stroke. I am a novice on this machine, I thought I was well below the maximum cut per stroke.
I am no longer trying to use a vise for this job.
I agree the shaper can take some serious cuts. Those are usually taking a cut on one side of the tool, and the tool is ground to cut only from one side. Is your tool ground to take the cut from both sides, and the bottom? A neutral rake on any sides of the cut will take a lot more force to cut, and therefore will require that much more clamping on the table.

I would look into designing a fence to take the force from the rack, and prevent it from bending. The stronger the fence, the less pressure you will need on the clamps holding the rack.
 

Reeltor

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#12
Superburban,

I used a 5 degree rake off the bottom and sides to give relief. I tried to make it the same way as a keyway cutter. The bit is honed on both sides and the bottom. I am using a 3/4" piece of NOS (REX or Circle) tool bit for rigidity.
 

f350ca

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#13
I made 3 racks for a CNC plasma table a few years ago. A lot smaller than your working with but the principals can be scaled. I needed the tooth placement to be as accurate as possible in order for the cnc to be accurate. I used the vertical mill to drill and ream holes for dowel pins down the length of the material at 6 or 8 inch spacing. Then made 3/4 x 2 plates with reamed holes to accept the same dowel pins. The plates bolted to the shaper table.

IMG_0835.jpg


Made a solid mount, your angle iron method would be similar but I'd expect the angle to flex. With the dowel pins through the two plates it was held down quite solid.
I added a DRO to the machine to space the teeth. After cutting a section i could index the material over on the dowels and reset the DRO the known distance I moved the material. Only the rear plate was removed to index the stock, the front plate held my reference.
I cut the three of them at once, in the end I could rotate one 180 degrees and the teeth meshed end to end so the indexing worked.

As Superburban suggested try rotating the cutter head as you would threading so your only cutting on one side. Worked for me.

IMG_0890.jpg


If I remember I was taking 10 or 12 thou cuts at the beginning then 1 or 2 thou cuts at the full depth. Didn't have the luxury of power down feed, still don't on my 18 inch Peerless.
Hope that gives you some ideas.

Greg
 

Reeltor

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#14
I made 3 racks for a CNC plasma table a few years ago. A lot smaller than your working with but the principals can be scaled. I needed the tooth placement to be as accurate as possible in order for the cnc to be accurate. I used the vertical mill to drill and ream holes for dowel pins down the length of the material at 6 or 8 inch spacing. Then made 3/4 x 2 plates with reamed holes to accept the same dowel pins. The plates bolted to the shaper table.

View attachment 257117

Made a solid mount, your angle iron method would be similar but I'd expect the angle to flex. With the dowel pins through the two plates it was held down quite solid.
I added a DRO to the machine to space the teeth. After cutting a section i could index the material over on the dowels and reset the DRO the known distance I moved the material. Only the rear plate was removed to index the stock, the front plate held my reference.
I cut the three of them at once, in the end I could rotate one 180 degrees and the teeth meshed end to end so the indexing worked.

As Superburban suggested try rotating the cutter head as you would threading so your only cutting on one side. Worked for me.

View attachment 257118

If I remember I was taking 10 or 12 thou cuts at the beginning then 1 or 2 thou cuts at the full depth. Didn't have the luxury of power down feed, still don't on my 18 inch Peerless.
Hope that gives you some ideas.

Greg
Greg,
Thank you for the photos, they are a real help; I like your idea better than using the angle iron. In your last photo, I see that the clapper box is angled but it looks like the tool bit is set perpendicular to the work, effectively cutting on both sides at once. What am I missing?
I'd like more information on your DRO for the shaper, can I impose upon you to ask you to either post info here or send me a message?

thanks,

Mike
 

f350ca

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#15
Yes the clapper is angled to match the pressure angle of the rack.The tool still needs to be perpendicular to the work, same as threading but it advances along the one side of the tooth, same as swinging the compound on the lathe.
I used I-Guaging DRO's on the Logan, worked great, was surpsided at the accuracy. Only problem with them is setting to a position, you can't enter the dimension, only zero them. I left them on it when I sold the shaper.
Wanted to put a DRO on the Peerless but the clapper retracts way into the housing on the back stroke. Wasn't enough room for a glass scale. Upgraded the mill to a 3 axis glass scale kit and transferred the old Shooting Star 2 axis I've had on it for 15 or more years. It used a small rack with an optical encoder to measure the movement. Quite compact, still a tight fit on the clapper though. The rack is round, the teeth are on the back side here.
IMG_3898.jpg


The cross feed was fairly easy to mount to. Funny they didn't cast nice mounts in these old machines for future DRO's
IMG_3899.jpg


Pretty simple readout. Reads to 1/2 thou

IMG_3900.jpg


Hope that helps Mike

Greg
 

Superburban

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#16
I think you have most of the bases covered, except for the the main question you asked. Sorry for side tracking so much. Greg's (F350CA) first two pics tell it all. With the blocks like that, you should be good to go to take the large cuts. remember, you need something like the block Greg has to keep the work piece from moving under the heavy cuts. After that, the actual hold down of the piece won't require as much pressure. I have done similar with using the big hold down clamps as a back stop, but will take Greg's idea, and make backstop, with the holes to make it easy to attach to the table.
 

benmychree

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#17
This is the exact method I used to cut the gear to mate with the rack. The length of the rack prohibits me from using the horizontal mill to cut the center out of each tooth. This is hot rolled steel, I am hoping not to have too much curling of the blank.
You can do long racks on a horizontal mill if you have the rack milling attachment, which has a cutter arbor at 90 degrees to the spindle axis; spacing is done with a change gear device with a one rev. detent; the sections of rack are held in a special vise, much like the one shown made out of rectangular bars, but is self contained. Also, rack can be made in sections, as many longer lathe carriage racks are.
 
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