Help w/cutting a gear on VN 22L

Reeltor · Dec 1, 2016

I have several questions on cutting a gear on my VN 22L.
1. What speed and feed to use? 2. Is the setup in the photo strong enough? 3. Shall I cut 14 or 15 teeth on the blank? I could buy a gear from Martin that has 15 teeth (4 dp 14-1/2 ° pressure angle. The charts that I reviewed say to cut 14 teeth in a 4” +- blank

The blank is 8620 steel, 4-1/32” Dia. 2” thick, I want to cut a gear with 4DP & 14 or 15 teeth. I am going to cut most of the waste material out using a 4” Staggered Tooth Side Mill cutter with 18 teeth that is .290 wide (4 x .290 x 1 ¼). I am seeing various numbers to use for SFM for 8620 (30 to 127). Using 50 sfm I come up with 50 RPM(47.7) and a feed rate of 1.7 IPM. The feed rate seems FAST to me.

What RPM and Feed would you use? 14 or 15 teeth and what dept of cut would you use? I want to use the gear to mesh with a rack for a kinetic style log splitter.
Looking at the photo, is the setup sufficient or to I need to do something more to secure the blank? Sorry for the long post, thanks for any help

Mike

onecut · Dec 1, 2016

The photo your showing I take it is an example that you have been looking at,Im guessing the blank is being held on to what looks to be some kind of expanding arbor and they have a straight tooth side and face in.What you are asking about the feeds and speeds you have worked out,they appear to be OK to use 50revs and 1.7feed you can always start at inch feed and increase it,as for roughing it out you can do that if you want to but if it was me I would just put your form tool in and go straight to depth.But as I dont have expanding arbors I just use a similar one to the photo but turn a thread on end so you can lock it on with a nut remember you want to cut the teeth without fouling your dividing head-Make sure you are feeding the correct way and have your tool on your arbor the correct way the photo has the cutter on that way for that particular machine must have a left hand thread on that arbor

Reeltor · Dec 1, 2016

onecut
The photo is of the setup on my machine, no it is not an expanding arbor. It is the arbor that will be used in the hope to finish log splitter. I've cut a keyway in the shaft and the gear blank, gear held in place using a set screw. The direction of the cut is a question. I do not have a left hand arbor for the mill and normally would want to reverse the milling cutter to go from left to right BUT everything I read says to mill from the footstock towards the Dividing Head. The gear blank/arbor is held in a NMTB 50 holder in the dividing head.

Should I flip the cutter around and cut from the Dividing Head towards the footstock?

Mike

johnoder · Dec 1, 2016

15 teeth would require a 4.25" blank

The way you do that is 17/4

16/4 does give 4" dia for 14 teeth

Feed rate if 18 teeth and 50 RPM means 900 teeth per minute - during which time its moving 1.7"

Divide the 1.7 by 900 and you get a chip load per tooth of a little less than .002" - not "fast" at all

Mike C. · Dec 1, 2016

I go the other way to figure feed. I get the rpm I need, then figure how much chipload per tooth and figure a feed rate from there.

.002 per tooth times 18 teeth is .036/rev. .036 times 50rpm is 1.8"/min. Close as your machine will run to those two numbers. 1 3/4ipm and 52rpm, 1 1/2ipm and 45rpm, it's just a ballpark figure.

DASunland · Dec 1, 2016

Reeltor said:
I have several questions on cutting a gear on my VN 22L.
1. What speed and feed to use? 2. Is the setup in the photo strong enough? 3. Shall I cut 14 or 15 teeth on the blank? I could buy a gear from Martin that has 15 teeth (4 dp 14-1/2 ° pressure angle. The charts that I reviewed say to cut 14 teeth in a 4” +- blank

The blank is 8620 steel, 4-1/32” Dia. 2” thick, I want to cut a gear with 4DP & 14 or 15 teeth. I am going to cut most of the waste material out using a 4” Staggered Tooth Side Mill cutter with 18 teeth that is .290 wide (4 x .290 x 1 ¼). I am seeing various numbers to use for SFM for 8620 (30 to 127). Using 50 sfm I come up with 50 RPM(47.7) and a feed rate of 1.7 IPM. The feed rate seems FAST to me.

What RPM and Feed would you use? 14 or 15 teeth and what dept of cut would you use? I want to use the gear to mesh with a rack for a kinetic style log splitter.
Looking at the photo, is the setup sufficient or to I need to do something more to secure the blank? Sorry for the long post, thanks for any help

Mike

View attachment 185322

For a 4P gear of 15 teeth blank= 4.250 inch Dia. and whole dept = 0.539
For a 4P gear of 14 teeth blank + 4.000 inch Dia. and whole dept = 0.539
As long as the roughing cutter width is less than the gear cutter width (compare with a caliper) it is ok

You will use the NO.7 out of the set
Gear cutters are expensive so a lower cutting speed is better for extending it's life
The cutter is around 4.625 dia.
I would use a cutting speed of about 45 SFM (for HSS) IF NO COOLANT, a little higher with coolant.
For feed: The cutter have 10 teeth, taking a.005 in per tooth per rev =.050 in per rev, times the revolution you will use per minute
will give you your feed per min.

Your setup looks good,blank a press fit on mandrel and held in a good collet chuck.

Reeltor · Dec 2, 2016

Thank you for taking your time to respond to the thread and giving me more ways to figure the math.

It was suggested that I use the form tool and go right to depth (.539"). One of the reasons that I'm going to use a straight tooth cutter to mill out most of the waste is that the set of Involute cutters that I bought off of ebay are not extremely sharp. I've stoned the face and can feel some improvement. I'm a hobby guy, so the extra time spent, will be well worth it. Especially if I don't do any damage to the mill. Richard Nixon was in office the last time I cut a gear :rolleyes5:

so your assistance is much appreciated.

Mike

Mike C. · Dec 3, 2016

If you get the feed too high, it'll hammer. When you get it all right with both the straight cutter and the involute, it's just a swishing sound. As DASunland says, better to err on the low side of speed without a coolant system. You aren't running a production line on piecework.

Reeltor · Dec 3, 2016

Mike C. said:
If you get the feed too high, it'll hammer. When you get it all right with both the straight cutter and the involute, it's just a swishing sound. As DASunland says, better to err on the low side of speed without a coolant system. You aren't running a production line on piecework.

Here is a question for you. The lowest RPM on the cutter head is 50. Is there a ratio between RPM and table Feed? I guess what I'm wondering about is do I keep the cutterhead at 50 RPM and run the feed a little slower until I see how everything works? I know I don't want the cutter to rub.
I don't have any trouble with normal cutters, it's the invloute form cutter and the setup on the dividing head that has me concerned. I don't what the setup to come loose upon the cutter entering the work.

Mike

Mike C. · Dec 3, 2016

Start with .0015-.002 chipload on feed and you should be fine. Old saying... speed burns, feed breaks. Little late if you push it all the way to that point, but something to think about. On the other hand, pushing the feed higher keeps the cutter biting fresh cool metal and forces the heat into the chips. As usual, it's all a compromise. You push the feed hard as you can without knocking your work loose, breaking cutter teeth or causing the machine to hammer and try to set the speed so that your chips are coming off straw colored, at the hottest.

A little coolmist system can do wonders on a setup like this, or just a squirt bottle of Tru Tap oil. Oil smokes like hell, though.

onecut · Dec 3, 2016

Reeltor,So its a log splitter that you have in your picture.Well its all about opinions I wouldnt be happy with that blank held on by a set screw its more than a possibility it could vibrate loose as for your machine arbor it all depends what thread you have on that arbor, you should in a perfect world be cutting so the force of cut is locking the arbor.Only you know what thread your arbor has so beware of cutting in the wrong direction as it will unlock your arbor.So for me it would be 40revs and 1-inch feed increase if you want to when your satisfied its coping

Reeltor · Dec 3, 2016

Mike C. said:
Start with .0015-.002 chipload on feed and you should be fine. Old saying... speed burns, feed breaks. Little late if you push it all the way to that point, but something to think about. On the other hand, pushing the feed higher keeps the cutter biting fresh cool metal and forces the heat into the chips. As usual, it's all a compromise. You push the feed hard as you can without knocking your work loose, breaking cutter teeth or causing the machine to hammer and try to set the speed so that your chips are coming off straw colored, at the hottest.

A little coolmist system can do wonders on a setup like this, or just a squirt bottle of Tru Tap oil. Oil smokes like hell, though.

Old saying... speed burns, feed breaks---makes sense. I will use Koolmist, I'm not sure if I want to use flood or just put some coolant in a 1 quart pressure style spray bottle so I can see what's going on.

Reeltor · Dec 3, 2016

onecut said:
Reeltor,So its a log splitter that you have in your picture.Well its all about opinions I wouldnt be happy with that blank held on by a set screw its more than a possibility it could vibrate loose as for your machine arbor it all depends what thread you have on that arbor, you should in a perfect world be cutting so the force of cut is locking the arbor.Only you know what thread your arbor has so beware of cutting in the wrong direction as it will unlock your arbor.So for me it would be 40revs and 1-inch feed increase if you want to when your sattisfied its copeing

So here's the rub, the dividing head is designed to sit on the left side of the table. Everything I've read and seen on-line says to machine towards the dividing head. No, I don't have a left hand arbor so you are correct the arbor nut and/or the drawbar can unscrew. All I can do is snug everything down tight and check often. I will NOT climb mill :rolleyes5:

As for the set screw and key holding the gear on the arbor when in the log splitter. If it looks like it will work loose, I'll put a weld on it.
You input and cautions are welcome.

thanks

Mike

onecut · Dec 4, 2016

Sure things will be OK for you,but at least you know about what to look out for. The arbor lock whilst cutting and your set screw holding method just keep an eye on both.If your machine has flood coolant on use it as thats what ruins cutters no coolant. And it helps the cutter cut the material so use it if you have it- have heard all this rubbish before off people who have burnt expensive cutters out and say I didnt have coolant on as I cant see whats happening-No way get the coolant on.Never climb mill unless your machine has an anti backlash eliminator on.Yes in a perfect world cut towards the headstock-My D/H goes on the right so I dont get all these unnecessary problems

Reeltor · Dec 8, 2016

Just wanted to give an update. I've cut 5 of the 14 slots; the mill is hammering a little until the cutter is entirely in the work. Then like Mike C said it's just a swishing sound. I noticed the arbor support moving around a little, so I'm going to fab up a quick and dirty outboard support. I think when everything is good an rigid it will cut fine.

Mike

Mike C. · Dec 8, 2016

Outboard support does wonders for the 22L. The arbor support wants to pivot around that single round overarm without it.

Ohio Mike · Dec 8, 2016

Some inspiration

brockwood · Apr 27, 2017

WOW! As a rank amateur, I am impressed both with the gear cutting setup on the 22L & the help received here! I noticed only 1 arbor support in use. I take it only the outboard support can prevent the dreaded pivot? I'll be making an outboard support for my 24MLA at some point. Would aluminum be correct (same as arbor support material)? What thickness would you all recommend?

ramsay1 · Apr 29, 2017

This is a good video on gear cutting.. Thanks to Ed for sharing..

cutting a spur gear vintage film - YouTube

Ramsay1

Mike C. · Apr 29, 2017

The issue is not so much pivoting as just vibration and chatter transferring down the overarm. Being it is round and not box shaped (like the later 1 and 2R series), the arm will tend to move in not only up and down, sided to side, but also in a twisting moment. The outboard bracket (not to be confused with outboard support, which would be a second arbor support out at the end of the arm, as well as one with a running bushing somewhere between the spindle and cutter), takes ALL that movement away. The original is cast iron, but steel or even aluminum would work. The only slightly complicated part of the build is the dovetail for the saddle V.

Help w/cutting a gear on VN 22L

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