PDA

View Full Version : Hercus Change Gear Guard



pipeclay
27th Aug 2008, 06:28 PM
Could a member please post a picture of the Change Gear Guard for a 9" model lathe.

I have just put a quick change box on my C ,and would like to see or find out how the Gear cover attaches to the front of the Quick chang if it does at all.

The other allternative I was going to do was just run a bit of metal in a vertical position with a hole in it and secure the Gear guard to that.

Also would any member have any idea as to what feed rates are available when using the Metric transposing gears,( I can go through and work it out but it will take me a while,just thought I maybe able to cheat and get them off someone) thankyou.

neksmerj
28th Aug 2008, 02:52 AM
Pipeclay,

The rear guard attaches to the bed of the Hercus, via a cast iron block that clamps onto the vee behind the head stock, left end. Will take some snaps for you over the weekend.

Ken

pipeclay
28th Aug 2008, 09:19 AM
Thanks Ken, but what does the front of the Guard attach to,I allready have the rear support arm, orriginally the Guard mounted at the front to the Leadscrew support housing.

Now that it has been removed the Guard is swinging in the breeze.

wannabe
28th Aug 2008, 11:55 AM
Pipeclay,
That's all mine does is swing in the breeze. It has no form of fixing at the front it just closes up against the quick change box.
The pic is not a good one but it's the only one of have around that area.

pipeclay
28th Aug 2008, 01:15 PM
Thankyou I may have to make the tab I was thinking of to secure it.

wannabe
28th Aug 2008, 01:29 PM
I haven't really taken much notice of mine other than to note that it doesn't swing too freely and has a small amount of tension which can be felt when openg/closing it. I don't know what causes this tension but I'll have a closer look later on and get back to you. When I first got the lathe I though this doesn't look too secure but it stays in place unless you bump it.

neksmerj
28th Aug 2008, 09:15 PM
Pipeclay,

On my Hercus, there is no catch on the front of the guard, to stop it from swinging open.

There is however, a thumb screw threaded into the cast iron mounting arm at the rear, where a limited amount of friction can be introduced to the swivel pin.

A drawing is attached, as mine was missing and had to make one.

Ken

wannabe
28th Aug 2008, 09:53 PM
I'll be buggered. The things you learn in this forum! I didn't even know there was supposed to be a thumb screw back there. Just had to go and check. Sure enough there's a hole back there but no screw in it. It's long since gone walkabout.
Pipeclay,
The slight tension I mentioned when moving the cover is only caused by the weight of the cover itself acting on the pivot point.

pipeclay
29th Aug 2008, 03:17 AM
Thanks to all for the helpfull tips ,Mine dosent seem to have any holes in the support arm might just have to drill and tap and make a locking screw as supplied by Ken.
Thanks again (anything to keep the swarf away from the gear train).

Drummond
29th Aug 2008, 11:30 AM
Regarding metric transposition, a drawing of the gear table plate for the 127/100 set is in Textbook of Turning.

If you have the later 63/50 set, Axmell may be able to help with an appropriate table.

Tony

neksmerj
29th Aug 2008, 12:52 PM
Pipeclay,

Attached is a snap of my rear guard support arm complete with square headed fixing screw and thumb screw as mentioned above.

The tapped hole is midway along the boss.

Hope this throws a little more light on the subject.

Ken

pipeclay
29th Aug 2008, 02:34 PM
Thanks Ken as I said mine dosent have the hole provision in it due to the fact that it was a "C" guard,I will drill and tap to take the thumb screw,thanks again.

Drummond what I was trying to find was what feed rates I could have while using the metric gears rather than changing them back to imperial to suit the quick change data plate,I done some calculations and now have a good idea of what feeds I can also obtain.

wannabe
1st Sep 2008, 03:35 PM
Pipeclay,
I don't know if you still need it but I found on the Yahoo Groups southbend10K site the attached Excel spreadsheet used for calculating feed rates on the 9A. Have a look under the 'Standard Gear Box Feeds' tab. I've had to edit the spreadsheet a bit deleting a couple of the worksheets to get it under the size limitations. The full spreadsheet can be downloaded from the files section of the above Yahoo group.

A dumb question. I'm having troubles understanding the feed rates stated on the standard imperial faceplate. For the 224 tpi position (E8) it states the feed rate is .0015". What is this .0015"? Is it distance travelled per rovolution. I initially thought it was Inches per minute (IPM) but that would be dependant on RPM so it can't be that.

pipeclay
2nd Sep 2008, 12:59 AM
The feed rates stated are for each revolution of your lead screw.
The carraige will advance .0015"

wannabe
2nd Sep 2008, 11:58 AM
Thanks. Understand now. IPM = IPR * RPM

pipeclay
2nd Sep 2008, 02:04 PM
You will probably find that on mills you will find feed rates in inches/minute,due mainly to the fact that there feed mechanism is inpependant of the main drive shaft (not working through gears).

wannabe
2nd Sep 2008, 02:26 PM
That's what was confusing me. I understand the relationship now.
I've come to grips with SFM, diameters and RPM and have been trying to understand feed rates on both the mill and the lathe. All I've been doing so far is unscientifically using a feed rate that I thought may be about right. Not having any experience with using the correct feed rates makes it a bit hard to judge if what I was doing was correct. Now I understand that and have a formula I can calc it so I know what I should be doing.

pipeclay
2nd Sep 2008, 03:36 PM
When it comes to useing the lathe the feed rates are quite often dependant on rigidity of machine,type of tooling.method of work holding and material being machined.
Another consideration to think of when working out feed rates is the nose radious of the tool particularly when using tiped tools,generally the bigger the nose radious the higher the feed rate,I my self try for .002-.004 when using .04 and tips ,and .004-,008 when using .08 tips.
You will soon see how the lathe likes the feed rates if it starts to bog down or vibrate you may have to play with the feed rates untill you reach a happy medium,a lot of it can be trial and error when using smaller HP machines.
Using HSS can be another ball game alltogether.